Sure if they want to. And then they have trade issues with the US, which is what that becomes: an economic conflict (which can easily become a military conflict

Sure if they want to. And then they have trade issues with the US, which is what that becomes: an economic conflict (which can easily become a military conflict). The US economy is drastically larger than the EU economy at this point (soon to be double the size), we control the global reserve currency, and provide a very large military shield across the EU (currently keeping Russia from attacking numerous smaller European nations). The US can do a lot more damage to Europe than the other way around, if it's conflict that Europe seeks with the US (whether economic or military). The same is true with US allies in Asia (particularly Japan, South Korea, Taiwan, Australia). All the US has to do is look the other way and Russia and China will get to work destroying the status quo, which includes ripping apart Europe and Asia. The US can feed Asia to China anytime it wants to, that includes Australia + New Zealand; it obviously doesn't want to do that. I think US allies want to keep the US an ally for all the right reasons, both economically and militarily.