Post 9/11 the US unilaterally changed the rules of the game, they had significant international sympathy - and the military/diplomatic/economic superpower status did not exactly encourage other states to be too vocal in their complaints. They significantly weakened their position on human rights (enhanced interrogation techniques, Gitmo etc.) and on the norms of international sovereignty (kidnapping foreign nationals in other countries AKA extraordinary rendition) and this week we have seen military strikes in Pakistan and Somalia (presumably by US forces).
What is sauce for the goose is sauce for the gander. Having changed the rules others have taken the opportunity to jump on the band waggon. Now it is the 'new norm' for any tin pot nasty-piece-of-work who has control of their countries military - regardless of how they got there - to call anyone they want to get rid of a terrorist and massacre them. If that includes extremely repressive tactics (Russia vs Chechen's, IDF vs Lebanon) or forays into another country (Turkey/Iraq, Colombia/Ecuador) then the new rules say no problem - as long as you remember to call whoever you want to attack a terrorist.
If the US intends to make the rules and then enforce them then they must expect to have to face vastly increased opposition across the board; friends shift to neutral, neutral to hostile and hostile to terrorist.
Just my $.02