I don't know if the US would have cared enough to join, especially if it happened during their conflict with Canada. The US was isolationist for a lot longer in PoW. They may have condemned the attacks and it may have damaged relations with the US, as well as with other South American nations, but it's not guaranteed the US would have become involved. Ask Byrd, though. As for relations with Panama.. well, obviously they wouldn't take kindly to it. But I don't think Panama would be able to retaliate. I did some quick research and their military history can be described as 'non-existent'. It's more likely other South American nations would have done something about it.