no voting up or down, just my 2 cents from europe:
US likes peace, if it helps economically (ie getting stuff from given place cheaply, selling your produce well.. you get the idea).
US doesn't care about peace, and will take any excuse to start a war, kill millions, make life extremely miserable for additional huge amounts of people (yes, tens of millions easily) if it's worth the goal. Which can be economical, power, or, as usually, mix of both. so many examples of murders of officials, nazi-style staging of attacks to get a foot into war (Tonkin bay, anybody?) etc. No my dear, war is a great business, is you are providing right products or services.
to cover this topic properly I would have to spend rest of evening just writing, and my knowledge of reality is anyway severely limited, as things like Snowden leaks reveal. US is not a single panel or one central brain, but composed of individuals, powerful, twisted, fucked up greedy bastards, who will do anything to get more (power, money) not because they need it, just because they can and their egos get kick from it. then you have the good guys in politics, who are honest, hardworking for people who voted them and not those who gave millions to campaigns to get them where they are in first place... NO. there are no such people, even if they were, they would be discredited easily by first group, or anyhow removed. Most I would say are somewhere in between. If you think army in level of general and higher is anything else than similar politics, think again (it isn't).
Is it in interest of US to have strong states in Gulf area, sitting on biggest oil reserves in this world? I don't think so, command and conquer is a proven strategy for millenia. US tried to help, but selectively, and mostly marginaly (if you help my enemy, you become my enemy is common logic all around the world). I still haven't heard a proper jsutification why US is still in Afghanistan when it lost that war, there is no will of winning it, and daily they are just killing more and more locals. US may conveniently label them terorists, but they are locals, fighting invading force (external fighters omitted).
Or training ukraininans? Just on the border of Russia? That's one hell of a peace move right there :) I am disgusted with US, don't expect anything good in terms of world politics coming out of it, and percieve it as necessary evil. Very happy seeing nations like Chinese rising to power. All empires rise and fall, ours and yours are no exceptions.