History shows, most of the major empires bullied the enemies/weaker ones to their way to the top and continued to bully the enemies/weaker ones to remain at the top. The only exception to this, I can think of was Ashoka, the Indian emperor of 2nd century BC (after conquering Kalinga he abondoned wars). So, in the current case, US is also no exception, the same goes for Britain a century ago and not to forget, every invading army in history done the same by exterminating the local helpless population of the native lands.
We are progressing fast in modern world with regards to science/technologies/gadgets etc., but our moral/ethical standpoint have always remained coloured and selective with regards to what we perceive wrong and right. Basically, we cherry pick the truth/half-truth/lies that suits for our psychological and moral well-being.
The only question that needs to be asked is, does the rest of the nations can sleep over the current issues happening all around the world whether in the name of religion/region/ideology etc., since it has not affected them? Or waiting for the WWIII to exterminate all living souls on this planet?
Er no.
Asoka's one example, what about:
1) Hebrew settlement of the Near East in about 1200 BC. Involved minimal bloodshed.
2) Muslim conquest of the Near East in the seventh century. Involved minimal bloodshed, at least during that timeframe (620-660); also Muslim expansion to Indonesia/SE Asia which was literallly carried forth by traders and sailors
3) Byzantine conquest of Ctesiphon in the early seventh century; relatively little bloodshed
4) Umayyad settlement of Spain in 750, minimal bloodshed.
5) Muslim Ayyubid takeover of Syria, Egypt and Palestine in the late 12th century. Minimal bloodshed.
6) Even the Mongols, known for their incredible savagery against their enemies, made it a point to stick to their treaties. If they allied themselves with somebody, they made it a point to respect that ruler's requests in the treaty. Those who refused alliance, though, were brutally slaughtered.
7) British takeover of S Asia. Involved relatively little bloodshed. The real bloodshed came when they disrespected local customs and the Indian citizens fought back in 1857; till then most of the bloodshed was confined to the battlefield.
8) American war of 1776. Involved generally close/intimate parties fighting and when possible, such as the siege of Yorktown, efforts were made for minimal bloodshed.
And these are just off the top of my head. The point is that although repression and cruelty is the norm (Romans, Barbary Corsairs, Normans, etc.) it is VERY possible to spread your influence and power without hacking and savaging anybody you feel like. Not to mention that America is a signer of dozens of international alliances and treaties, which they freely shun whenever they like.