Europe can bring America to its knees any time it wants by imposing sanctions. The US economy is increasingly dependant on foreign investment, proper sanctions would be just enough to push it over the edge. However, this would hurt the EU's economy, which is a big reason why they aren't doing it. From their perspective, some lost oil contracts aren't worth tanking the whole economy over. They'll whine about it, but it's just not worth it for the European ruling class. It's just some dead brown people - not something they value very highly. Plus the US and EU still have lots of other common interests, like keeping the "third world" down and maintaining global capitalism. Modern capitalism is integrated on a global scale through multinational corporations and the like, it needs a world authority to hold the system together and act as galactic enforcer. The American empire currently acts as that enforcer, but imperfectly so from the perspective of the world's elites since it tends to favor its own interests at their expense. If European and other elites actively attempted to overthrow the American empire and suceeded they'd have screwed themselves because they'll have destroyed what is currently an essential componet in global capitalism. They could attempt to set up a supra-national "peacekeeping" authority to enforce global capitalism, but they will not move against the US unless forced to do so until it is set up.