"American" isn't a race but the internet commenter love affair with shitting on the USA is kinda played out. We're not perfect, sometimes we're not even all that good but it takes a special kind of delusion to ignore our efforts to promote peace and stability over the past century or so.
An easy counterpoint would be things like forever wars in the Middle East, shady CIA bullshit pretty much anywhere they think they can get away with it and other agencies that probably know me more intimately than my proctologist. Generally, I'd agree that there's a lack of effective oversight and some poor decision-making at play. There's a lot of work to be done but our slow, drunken stumble is still moving toward a better future more often than not.
Speaking of the future: you're probably the least corrupt of all the superpowers fucking the environment, but that's not saying much. I think the US will need real democracy soon.
Least corrupt is a start, I'll take it over some alternatives. Probably helps that our whistleblowers have a better than average survival/not-getting-disappeared rate and are often seen as heroes by the public. I don't know what it'll take to fix the rest of our issues, just hope to see a little less backsliding and more reasonable engagement while working out of this angsty teenager phase thing we've got going on.
The USA is the biggest weapon exporter and have been at war for about 95% of time it exists. They have been meddling in political affairs all over the world, setup puppet governments wherever they can, and deem foreigners as second class humans in their laws.
If that is your way of "promoting peace" please stop.