e Second Circuit has made very clear that, for purposes of the FSIA, a commercial activity must be one in which a private person can engage lawfully. Letelier v. Republic of Chile, 748 F.2d 790, 797-98 (2d Cir.1984); see also Saudi Ara- bia v. Nelson, 507 U.S. 349, 360-62, 113 S.Ct. 1471, 123 L.Ed.2d 47 (19