1989, shortly before they went to Panama for Noriega et Al. I can't find any reference that suggests US courts held contrary opinions.
Extraterritorial Effect of the Posse Comitatus Act
November 3, 1989
Memorandum Opinion For The Assistant To The President For National Security Affairs
You have asked for our advice whether the Posse Comitatus Act, 18U.S.C. § 1385, applies outside the territory of the United States. We conclude that it does not. Neither the language, history, nor legislative history of the Act suggests that Congress intended for the Act to apply extraterritorially. Under these circumstances, established rules of statutory construction impose a presumption that the Act is to be construed as having only domestic effect. Such a construction is necessary to enable criminal laws with extraterritorial effect to be executed and to avoid unwarranted restraints on the President’s constitutional powers. Additional legislation and accompanying Department of Defense regulations authorizing certain types of military assistance to civilian authorities contain some suggestion that restrictions on military assistance enumerated therein apply outside the land area of the United States. We believe, however, that the better view is that these rules must be read consistently with other provisions in the same legislation providing that no limitations beyond those imposed by the Posse Comitatus Act were intended to be enacted. The scope of the regulations will be subject to some uncertainty, however, until they are amended to expressly state these limits on their scope.