215 F.3d 727 (7th Cir. 2000)
EDWARD HAVEN and ALLEN WELBEL,    Plaintiffs-Appellants,v.RZECZPOSPOLITA POLSKA, SKARB PANSTWA,  State Treasury of Poland, POWSZECHNY   ZAKLAD UBEZPIECZEN S.A.,    Defendants-Appellees.
No. 99-3823
In the  United States Court of Appeals  For the Seventh Circuit
Argued April 6, 2000
Decided June 8, 2000

Appeal from the United States District Court  for the Northern District of Illinois, Eastern Division.  No. 99 C 1727--Milton I. Shadur, Judge. [Copyrighted Material Omitted][Copyrighted Material Omitted]
Before POSNER, Chief Judge, and FLAUM and RIPPLE,  Circuit Judges.
RIPPLE, Circuit Judge.


1
Edward Haven and Allen  Welbel brought this action seeking the return of  property allegedly belonging to them and their  families. They claim that the property was seized  by the Polish government after World War II. The  district court dismissed the action on the ground  that it lacked subject matter jurisdiction. For  the reasons set forth in the following opinion,  we affirm the judgment of the district court.

I  BACKGROUND1

2
Edward Haven and Allen Welbel both emigrated  from Poland to the United States after World War  II because of the Polish government's anti-  Semitic policies. Both of them left behind real  property owned by their families. Mr. Haven's  property was insured by Powszechny Zaklad  Ubezpieczen ("PZU"), a Polish insurance company.  Mr. Haven and Mr. Welbel allege that their family  lands were illegally seized by the state, and Mr.  Haven also alleges that PZU failed to honor its  insurance contract. PZU itself was nationalized  by Poland after World War II.


3
In 1960, Poland and the United States entered  into a treaty by which Poland agreed to  compensate United States nationals for property  seized by Poland after World War II (the  "Treaty"). The Treaty provided that Poland would  pay $40,000,000 in full settlement of all claims  made by nationals of the United States. The  United States set up an administrative procedure  by which its nationals could obtain a portion of  the settlement.


4
In March 1999, Mr. Haven and Mr. Welbel brought  this action in the district court.2 The  complaint sought the return of property and  damages from the Republic of Poland and the State  Treasury of the Republic of Poland (collectively  "Poland"). It also sought damages from Poland for  interfering with PZU's contracts and from PZU for  failing to perform its contracts. Mr. Haven and  Mr. Welbel served process on the Polish  government on May 7. On July 8, the Polish  Consulate in Chicago delivered a letter to the  district court, purporting to express the Polish  Ministry of Justice's view that service was  improper under the Convention on the Service  Abroad of Judicial and Extrajudicial Documents in  Civil or Commercial Matters (the "Hague  Convention"). The district court postponed a  default hearing scheduled for July 12, and on  July 13 counsel for Poland and PZU entered an  appearance.


5
On August 10, Poland and PZU filed a motion to  dismiss the case on several grounds, including  lack of subject matter jurisdiction due to  sovereign immunity. There is no dispute that all  of the defendants in this case are "foreign  states" within the meaning of the 1976 Foreign  Sovereign Immunity Act ("FSIA"), 28 U.S.C. sec.  1602 et seq. The district court entered an order  on August 24 holding that the FSIA could be  applied retroactively to claims arising before  its passage. On September 29, the district court  ruled that it lacked subject matter jurisdiction  because the action did not fall within any of the  exceptions to the general rule that foreign  sovereigns are immune from suit in United States  courts. First, the court held that the Polish  Consulate's July 8 letter was not a knowing  relinquishment of rights that waived sovereign  immunity.3 Second, it held that the Treaty had  not expressly waived sovereign immunity.4 Third  and finally, the district court found that PZU  had not waived its sovereign immunity by  undertaking commercial activity in the United  States.

II    DISCUSSION

6
We review de novo a district court's dismissal  for lack of subject matter jurisdiction. See  Fedorca v. Perryman, 197 F.3d 236, 239 (7th Cir.  1999); Kaplan v. United States, 133 F.3d 469,  472-73 (7th Cir. 1998). Foreign sovereigns  historically enjoyed immunity from common law  suit in United States courts. See In re Air Crash  Disaster Near Roselawn, Ind., 96 F.3d 932, 945-46  (7th Cir. 1996); Goar v. Compania Peruana de  Vapores, 688 F.2d 417, 425-26 (5th Cir. 1982).  The FSIA provides a statutory codification of  that immunity. See Verlinden B.V. v. Central Bank  of Nigeria, 461 U.S. 480, 488 (1983); Employers  Ins. of Wausau v. Banco De Seguros Del Estado,  199 F.3d 937, 941 (7th Cir. 1999); Wolf v.  Federal Republic of Germany, 95 F.3d 536, 540-41  (7th Cir. 1996). The FSIA also provides  exceptions to the rule of sovereign immunity. See  Verlinden, 480 U.S. at 488; Wolf, 95 F.3d at 541.  Because those exceptions are in derogation of the  common law, we must not read them broadly.  Statutes in derogation of the common law are  narrowly construed. See Norfolk Redevelopment &  Housing Auth. v. Chesapeake & Potomac Tel. Co.,  464 U.S. 30, 35 (1983); In re Liberatore, 574  F.2d 78, 85 (2d Cir. 1978); Picker v. Searcher's  Detective Agency, 515 F.2d 1316, 1319 (D.C. Cir.  1975).

A.

7
Mr. Haven's and Mr. Welbel's first argument that  jurisdiction is appropriate relies on the letter  mailed to the district court by the Polish  Consulate. Mr. Haven and Mr. Welbel contend that  this letter brings Poland within an exception to  sovereign immunity:


8
A foreign state shall not be immune from the  jurisdiction of courts of the United States or of  the States in any case in which the foreign state  has waived its immunity either explicitly or by  implication, notwithstanding any withdrawal of  the waiver which the foreign state may purport to  effect except in accordance with the terms of the  waiver.


9
28 U.S.C. sec. 1605(a)(1). If a sovereign files a  responsive pleading without raising the defense  of sovereign immunity, then the immunity defense  is waived. See Frolova v. Union of Soviet  Socialist Republics, 761 F.2d 370, 377 (7th Cir.  1985) (per curiam); accord Drexel Burnham Lambert  v. Committee of Receivers, 12 F.3d 317, 326 (2d  Cir. 1993); United States v. Crawford Enters.,  643 F. Supp. 370, 378-79 (S.D. Tex. 1986). The  letter sent by the Polish Consulate to the  district court did not raise any sovereign  immunity defense; therefore, if the letter was a  responsive pleading, sovereign immunity has been  waived. Mr. Haven and Mr. Welbel argue that the  letter was a responsive pleading.


10
Rule 7 of the Federal Rules of Civil Procedure  explains that only certain filings may be  considered responsive pleadings, including a  complaint, an answer, a reply to a counterclaim,  an answer to a cross-claim, a third-party  complaint, and a third-party answer. "No other  pleading shall be allowed." Fed. R. Civ. P. 7. A  responsive pleading need only be filed after  proper service has been made. See Silva v. City  of Madison, 69 F.3d 1368, 1376 (7th Cir. 1995)  ("[A] responsive pleading is required only after  service has been effected and the party has been  made subject to the jurisdiction of the federal  courts."); Bowman v. Weeks Marine, Inc., 936 F.  Supp. 329, 336-37 (D.S.C. 1996).


11
Although objections to service of process may be  made in a responsive pleading, they may also be  made through a Rule 12 motion to dismiss. As Rule  12(b) explains:


12
Every defense, in law or fact, to a claim for  relief in any pleading . . . shall be asserted in  the responsive pleading thereto if one is  required, except that the following defenses may  at the option of the pleader be made by motion: .  . . (5) insufficiency of service of process.


13
Fed. R. Civ. P. 12 (emphasis added). We have  acknowledged that the insufficiency of service of  process may properly be raised through a motion  to dismiss. See, e.g., Troxell v. Fedders of  North Am., Inc., 160 F.3d 381, 382-83 (7th Cir.  1998) (affirming district court's grant of  defendant's "motion to dismiss" for insufficient  process). A motion to dismiss is not a responsive  pleading. See Duda v. Board of Educ. of Franklin  Park, 133 F.3d 1054, 1056-57 & n.2 (7th Cir.  1998); Camp v. Gregory, 67 F.3d 1286, 1289 (7th  Cir. 1995); Scam Instrument Corp. v. Control Data  Assoc., 458 F.2d 885, 889 (7th Cir. 1972).5


14
The Federal Rules of Civil Procedure also  specifically contemplate that foreign sovereigns  will be allowed to object to the adequacy of  service. Rule 4, which governs service of  process, requires that service on foreign  sovereigns comply with 28 U.S.C. sec. 1608. See  Fed. R. Civ. P. 4(j)(1). The Hague Convention  itself is attached to Rule 4 as an appendix.  Article 4 of the Convention allows foreign  sovereigns to object to the service of  process.6


15
The Federal Rules of Civil Procedure, and our  case law interpreting those rules, require us to  hold that sovereign immunity was not waived by  the Polish Consulate's letter. The only court  filing that can waive a sovereign immunity  defense is a responsive pleading that does not  raise the defense. The Consulate's letter  objecting to the propriety of service is properly  treated as a motion to dismiss, not a responsive  pleading. See Hirsh v. State of Israel, 962 F.  Supp. 377, 380 (S.D.N.Y.) ("Although an implied  waiver may be found where a foreign state files a  responsive pleading that fails to raise the  defense of sovereign immunity, Germany's letter  is not a 'responsive pleading.'" (citation  omitted)), aff'd, 133 F.3d 907 (2d Cir. 1997).7  Indeed, until it was established that service of  process had been properly executed, Poland was  under no obligation to file any responsive  pleading. See Silva, 69 F.3d at 1368. Because the  letter was not a responsive pleading, its failure  to raise the sovereign immunity defense did not  compromise Poland's ability to raise that  defense.


16
Our holding that Poland's letter objecting to  service of process did not waive sovereign  immunity is consistent with Congress' requirement  that waiver on the part of foreign sovereigns be  knowing. We have written:


17
Congress anticipated, at a minimum, that waiver  would not be found absent a conscious decision to  take part in the litigation and a failure to  raise sovereign immunity despite the opportunity  to do so. The case law evidences a reticence to  find a waiver from the nature of a foreign  state's participation in litigation.


18
Frolova, 761 F.2d at 378. Poland's objection to  the adequacy of service was not "a conscious  decision to take part in the litigation"; indeed,  it was an indication by Poland that, at that  point, it did not intend to participate in the  litigation. Thus, Poland's letter objecting to  the service of process should not waive its  sovereign immunity.


19
We also cannot agree with Mr. Haven's and Mr.  Welbel's contention that their counsel's phone  conversations with employees of the Polish  Consulate led to a waiver of Poland's sovereign  immunity. Counsel for Mr. Haven and Mr. Welbel  telephoned the Polish Consulate, and counsel  claims that two Polish Consulate employees spoke  to him without raising the sovereign immunity  defense. Mr. Haven and Mr. Welbel argue that the  district court improperly ruled that the  employees did not have the authority to waive  sovereign immunity. The district court found  there was nothing to suggest that those employees  had the authority to waive Poland's sovereign  immunity. Even if those employees did have the  authority to waive sovereign immunity, they could  not do so in a telephone conversation. A  telephone conversation is not a responsive  pleading. Thus, we decline to find waiver from  any communications between counsel and the  Consulate.

B.

20
Mr. Haven and Mr. Welbel next argue that the  district court had jurisdiction because the  Treaty waived Poland's sovereign immunity. The  district court initially assumed that Mr. Haven  and Mr. Welbel were not United States nationals  in 1960 when the Treaty was signed; it ruled  that, even if the Treaty did waive Poland's  sovereign immunity, it could do so only as to  persons who were United States nationals in 1960.  After the district court ruled, Mr. Haven and Mr.  Welbel sought leave to establish that they were,  in fact, United States nationals at the time of  the Treaty. The district court then determined  that, if they were United States nationals at the  time of the Treaty, the Treaty itself would  foreclose their claim. Because we believe that  nothing in the Treaty contemplates a waiver of  Poland's sovereign immunity, we need not  determine whether Mr. Haven and Mr. Welbel were  United States nationals in 1960.

1.

21
The text of the Treaty contains no mention of  any waiver of sovereign immunity. It does not  even mention the availability of a cause of  action in the United States courts. There is  therefore no basis for finding that the Treaty  waived Poland's sovereign immunity. A foreign  sovereign does not waive its sovereign immunity  "by signing an international agreement that  contains no mention of a waiver of immunity to  suit in United States courts or even the  availability of a cause of action in the United  States." Argentine Republic v. Amerada Hess  Shipping Corp., 488 U.S. 428, 442-43 (1989); see  also Creighton Ltd. v. Government of the State of  Qatar, 181 F.3d 118, 123 (D.C. Cir. 1999); Smith  v. Socialist People's Libyan Arab Jamahiriya, 101  F.3d 239, 245-46 (2d Cir. 1997).


22
Even if Mr. Haven and Mr. Welbel had been United  States nationals in 1960, the Treaty could not be  said to waive Poland's sovereign immunity.  Indeed, the text of the Treaty makes plain that  Poland expected the Treaty to eliminate any  obligation it had to defend against claims by  United States nationals for nationalized  property. The President of the United States has  the authority to renounce or extinguish claims of  United States nationals against foreign  governments in exchange for lump-sum payments.  See Dames & Moore v. Regan, 453 U.S. 654, 679  (1981); Belk v. United States, 858 F.2d 706, 709  (Fed. Cir. 1988). The Treaty is an example of an  agreement between the United States and a foreign  sovereign that extinguishes all claims by United  States nationals. See Dames & Moore, 453 U.S. at  680 n.9; see also Schmidt v. Polish People's  Republic, 742 F.2d 67, 72 (2d Cir. 1984). The  text of the Treaty is clear. Article I describes  the lump sum payment made by Poland to the United  States as a "full settlement and discharge of all  claims of nationals of the United States." 11  U.S.T. 1953 at Art. I. That lump sum was to be  distributed "in accordance with such methods of  distribution as may be adopted by the Government  of the United States." Id. at Art. III. Thus, by  the terms of Articles I and III, the United  States replaced Poland as the country responsible  for ensuring that proper compensation was made to  United States nationals who owned land  nationalized by Poland.8 The language of the  Treaty makes explicit that Poland expected the  lump-sum payment to satisfy fully its duties to  United States nationals. It would be futile,  therefore, to allow Mr. Haven and Mr. Welbel to  prove that they were United States nationals in  1960 because the 1960 Treaty did not waive  Poland's sovereign immunity against United States  nationals.

2.

23
Mr. Haven and Mr. Welbel argue, however, that,  although the text of the Treaty does not waive  explicitly Poland's sovereign immunity, the  language nevertheless permits the invocation of  various exceptions to sovereign immunity. As we  explain in the following paragraphs, however,  these exceptions are not applicable.


24
Mr. Haven and Mr. Welbel submit that the Treaty  has waived sovereign immunity by designating that  American law would govern any contractual  disputes. At the outset, we note that no such  clause exists in this treaty. The portion of the  Treaty's annex cited by Mr. Haven and Mr. Welbel  is a discussion of what persons may seek  recompense under the Treaty; it does not provide  that United States law would govern any  contractual disputes. See Treaty Annex A(b)-A(d)  & B9 Moreover, although a sovereign may waive  implicitly its immunity through a contract if the  contract "stipulate[s] that American law should  govern any contractual disputes," Frolova, 761  F.2d at 377, courts have required a more explicit  waiver in the case of treaties, see id. at 378  ("[W]aiver by treaty is not included in the list  of examples of implicit waivers.").


25
Mr. Haven and Mr. Welbel also contend that,  through the language of the Treaty, Poland sought  assistance from the United States in protecting  against claims asserted through other countries.  Article V of the Treaty states that the United  States would provide to Poland copies of any  formal statements of claim. See Treaty at V.B.  This provision ensured that, once a United States  national was compensated through the Treaty,  Poland would have a record of that national's  claim being satisfied in order to prevent that  national from asserting another claim through the  government of another nation. Poland's request  for information about claims filed in the United  States does not make Poland amenable to suit in  United States courts or expressly waive its  sovereign immunity in those courts. Therefore, we  conclude that Article V does not waive Poland's  sovereign immunity.


26
In summary, we are not persuaded that the text  of the Treaty has waived Poland's sovereign  immunity. "Courts have generally required  convincing evidence that a treaty was intended to  waive sovereign immunity before holding that a  foreign state may be sued in this country."  Frolova, 761 F.2d at 378. There is nothing in this Treaty to suggest that Poland ever intended  to waive its immunity to suit in United States  courts under any circumstances. The text of the  Treaty does not waive Poland's sovereign  immunity, regardless whether Mr. Haven and Mr.  Welbel were United States citizens in 1960.

3.

27
When a sovereign has protected its immunity  through the language of a treaty, it may  nonetheless waive that immunity by its actions in  United States courts. If a foreign nation brings  an action in a United States court against a  United States citizen, it may waive its immunity  from suit by that individual. See Siderman v.  Republic of Argentina, 965 F.2d 699, 722 (9th  Cir. 1992) ("The evidence indicates that  Argentina deliberately involved United States  courts in its efforts to persecute Jose Siderman.  If Argentina has engaged our courts in the very  course of activity for which the Sidermans seek  redress, it has waived its immunity as to that  redress."). There is no allegation that Poland  ever "deliberately involved United States courts"  in any matter involving either Mr. Haven or Mr.  Welbel. Thus, Poland has not waived its sovereign  immunity by any action relating to the Treaty.

C.

28
Mr. Haven and Mr. Welbel's final argument that  the district court had subject matter  jurisdiction is based on the FSIA's commercial  activity exception. A foreign sovereign may waive  sovereign immunity by carrying on commercial  activity in the United States. The FSIA permits  jurisdiction in any case:    in which the action is based upon a commercial  activity carried on in the United States by the  foreign state; or upon an act performed in the  United States in connection with a commercial  activity of the foreign state elsewhere; or upon  an act outside the territory of the United States  in connection with a commercial activity of the  foreign state elsewhere and that act causes a  direct effect in the United States.    28 U.S.C. sec. 1605(a)(2). This subsection  requires that the lawsuit itself must be "based  upon" the commercial activity that supports a  waiver of sovereign immunity. See Saudi Arabia v.  Nelson, 507 U.S. 349, 358 (1993); Santos v.  Compagnie Nationale Air France, 934 F.2d 890, 892  (7th Cir. 1991) ("This Court and most others have  stated that the term 'based upon' requires an  'identifiable nexus' between the claim and the  commercial activity at issue."); Rush-  Presbyterian-St. Luke's Med. Ctr. v. Hellenic  Republic, 877 F.2d 574, 582 (7th Cir. 1989). The  Fifth Circuit has explained that "there must be a  connection between the plaintiff's cause of  action and the commercial acts of the foreign  sovereign." Stena Rederi AB v. Comision de  Contratos del Comite Ejecutivo General del  Sindicato Revolucionario de Trabajadores  Petroleros de la Republica Mexicana, S.C., 923  F.2d 380, 386 (5th Cir. 1991); see also Byrd v.  Corporacion Forestal y Industrial de Olancho  S.A., 182 F.3d 380, 389 (5th Cir. 1999) (quoting  Stena Rederi); In re Tamimi, 176 F.3d 274, 280  (4th Cir. 1999) (same).


29
The commercial activities alleged by Mr. Haven  and Mr. Welbel are internet advertisements for  insurance marketed by PZU and efforts by PZU to  market insurance to United States consumers.  Assuming without deciding that the alleged  activities constitute commercial activity in the  United States, these activities bear no relation  to the claims raised by Mr. Haven and Mr. Welbel.  Any current efforts by PZU to market insurance in  the United States have no relationship to PZU's  role in the nationalization of property in Poland  after World War II. Thus, this lawsuit is not  "based upon" commercial activity in the United  States, and the commercial activity exception of  the FSIA cannot apply.

Conclusion

30
For the foregoing reasons,10 the judgment of  the district court is affirmed.

AFFIRMED


Notes:


1
 When reviewing a dismissal for lack of subject  matter jurisdiction, we assume the truth of the  plaintiffs' factual allegations and consider  those allegations in the light most favorable to  the plaintiffs. See Komorowski v. Townline Mini-  Mart & Restaurant, 162 F.3d 962, 964 (7th Cir.  1998) (per curiam).


2
 Mr. Haven and Mr. Welbel sought appointment as  representatives of a class. The district court  never reached the issue of class certification.


3
 The court also held that Poland's objection to  the service of process was erroneous, and that  process had properly been served on Poland.


4
 The district court's order assumed that Mr. Haven  and Mr. Welbel were not United States nationals  at the time of the Treaty, and thus outside the  Treaty's scope. After Mr. Haven and Mr. Welbel  filed supplemental materials with the court  stating that they may have been United States  nationals in 1960, the district court issued an  October 4 supplemental order, finding that if  they were United States nationals in 1960, their  claims were foreclosed by the Treaty itself.


5
 Accord Bowden v. United States, 176 F.3d 552, 555  (D.C. Cir. 1999); United States ex rel. Saaf v.  Lehman Bros., 123 F.3d 1307, 1308 (9th Cir. 1997)  (per curiam); Barbara v. New York Stock Exch.,  Inc., 99 F.3d 49, 56 (2d Cir. 1996); Brever v.  Rockwell Int'l Corp., 40 F.3d 1119, 1131 (10th  Cir. 1994).


6
 Normally, the objection must be made by the  Central Authority of the foreign sovereign, which  informs the applicant of its objections. See  Hague Convention at Art. 4. In this case we are  not asked to decide whether Poland followed the  correct procedure under the Hague Convention in  its objection to service, only whether Poland's  objection to the service of process was in the  form of a responsive pleading.


7
 Mr. Haven and Mr. Welbel seek to distinguish  Hirsh on the ground that in that case, Germany's  letter to the court expressly reserved its  sovereign immunity defense, unlike Poland's  letter here. Although the court in Hirsh noted  language in Germany's letter reserving a  sovereign immunity defense, the court actually  relied on the fact that the letter itself was not  a responsive pleading. See Hirsh, 962 F. Supp. at  380.


8
 The United States fulfilled, through the Foreign  Claims Settlement Commission (the "FCSC"), its  obligation to make whole its nationals who owned  land seized by Poland. The FCSC has jurisdiction  to adjudicate claims brought by any United States  national arising under:    the terms of any claims agreement concluded on or  after March 10, 1954, between the Government of  the United States and a foreign government  (exclusive of governments against which the  United States declared the existence of a state  of war during World War II) similarly providing  for the settlement and discharge of claims of the  Government of the United States and of nationals  of the United States against a foreign  government, arising out of the nationalization or  other taking of property, by the agreement of the  Government of the United States to accept from  that government a sum in en bloc settlement  thereof.    22 U.S.C. sec. 1623(a)(1)(B). The FCSC disbursed  the funds obtained from Poland in the Treaty. See  Schmidt, 742 F.2d at 69 (discussing claims for  recompense under the Treaty filed with the FCSC).  The FCSC completed its administration of the  Polish Claims Program in 1966. See Foreign Claims  Settlement Comm'n, Twenty-Fourth Semiannual  Report to the Congress 37 (1996). FCSC decisions  may not be reviewed by a federal court. See 22  U.S.C. sec. 1622g.


9
 The portion of the Treaty Annex cited by Mr.  Haven and Mr. Welbel reads, in full:    A.  For the purpose of distribution by the  Government of the United States of the sum to be  paid by the Government of Poland, "claims of  nationals of the United States" are rights and  interests in and with respect to property  nationalized, appropriated or otherwise taken by  Poland which, from the date of such  nationalization, appropriation or other taking to  the date of entry into force of this Agreement,  have been continuously owned, subject to the  provisions of paragraphs B and C of this Annex,    . . . .    (b)  directly by juridical persons organized  under the laws of the United States or of a  constituent State or other political entity  thereof, of which fifty per cent or more of the  outstanding capital stock or proprietary interest  was owned by nationals of the United States;    (c)  directly by juridical persons organized  under the laws of the United States or of a  constituent State or other political entity  thereof, of which fifty per cent or more of the  outstanding capital stock or proprietary interest  was owned by natural persons who were nationals  of the United States, directly, or indirectly  through interests in one or more juridical  persons of any nationality;    (d)  indirectly by natural persons who were  nationals of the United States or by juridical  persons organized under the laws of the United  States or of a constituent State or other  political entity thereof, through interests in  juridical persons organized under the laws of the  United States or of a constituent State or other  political entity thereof which are not included  within category (b) or (c) above[.]    . . . .    B.  Juridical persons organized under the laws of  the United States or of a constituent State or  other political entity thereof which have been  reorganized through judicial proceedings after  their property or rights and interests in and  with respect to property were nationalized or  taken by Poland shall participate in the sum to  be paid by the Government of Poland only to the  extent that the outstanding capital stock or  proprietary interest in such juridical persons  was owned, at the time of such nationalization or  other taking, by natural persons who were  nationals of the United States, directly, or  indirectly through interests in one or more  juridical persons organized under the laws of the  United States or of a constituent State or other  political entity thereof.    11 U.S.T. 1953 Annex, at A(b)-A(d) & B.


10
 Because the district court lacked jurisdiction  over this matter, we need not consider the  alternate grounds for dismissal argued by Poland.


