Every govt in the world that goes to the UN has sufficient nexus to the United States - the court is a fifth column.
Besides, there’s still such a thing in New York State as Quasi In Rem jurisdiction. They have assets in New York, possession of those assets is sufficient nexus. Grab their f@#$ing bank account, in other words, and use it to satisfy the verdict, and the question of right to do so being sufficient nexus as the basis for an appeal to SCOTUS. This case is not over yet, but the Circus Court of Appeals’ insanity is worthy of comment.