--Why do you think that is?
How else can they make their presence felt? They can't compete in a natural way and they're just not psychologically prepared to be ignored.
Because we intimidate them. They can not compete with us militarily, economically and socially. We also compete with them for the resources they need for their burgeoning economies.
Don't think that for one instance that Russia is our friend. They are more like an acquaintance, with some shared interests. Push comes to shove, they will look out for their best interests, before risking anything to help the US; unlike our true allies.
China has always been an enemy, and will continue to remain so. They wish to be the preeminent power in the Pacific, and at least on par with the US globally. They also don't have any qualms about using military force to achieve those goals. Only reason we haven't traded blows with them so far is that they know we will kick their a$$e$. That could very well change, with the way they are expanding their military. Chances are, that we will be involved in a shooting war with China before the end of the century. My guess that it is either over Taiwan, or us assisting our allies in the Spratleys.
That's my 2 Cents, and I could be wrong.