@[deleted]
Look, I think we all can accept that "the situation is complex" or whatever, and that there are long-standing, generational traumas and sectarianism in the Middle East that would contribute to violent conflict even in the absence of imperial power. There is no one single actor—except possibly militarised capitalism—to which the constant churn of violence can be attributed.
With that in mind, here's a list of just some of the things the US has done in the region:
Masterminded the 1953 coup d'etat in Iran that led to the removal of Mossadegh's government (retribution for nationalising the oil industry)
Masterminded the 1963 coup d'etat that installed the Ba'ath Party in power in Iraq
Supported the Shah's oppressive regime via the CIA creating the conditions for the religious revolution
Uncritically pursued long-standing military alliances with Israel and Saudi Arabia
Condoned the spread of Wahhabism by Saudi Arabia perceiving political Islam as a counterweight to communism
Pursued a long-standing campaign against secular pan-Arabist and Ba'athist regimes
Insisted on the removal of Saddam Hussein from power irrespective of the consequences
Enforced sanctions on Hussein's regime in Iraq that led to estimated millions of deaths
Fabricated a "clash of civilisations" with Islam through ceaseless propaganda after 9/11
Invaded Iraq on a false pretext and without international approval
Withdrew from Iraq when nothing resembling a functioning nation remained of it, after hundreds of thousands of deaths
Installed the al-Maliki government which condoned the actions of Shia death squads throughout Iraq
Allowed an ungovernable Sunni-occupied region to form (possibly deliberately—cf NSA leaks) and subsequently become ISIS
Intervened in Libya through NATO, reducing the country to ruins in what is generally agreed to be a complete disaster
Insisted intransigently on the removal of Assad from power against strong opposition in 2011, through the UN and then a "special working group"
Refused to allow Assad to step down in favour of an internationally monitored democratic election in Syria in 2012 (because he still had popular support)
Given the CIA billions to train and arm "FSA rebels" who subsequently fought for JAN and ISIS
Condoned Turkish brokerage of ISIS oil extraction, allowing the ISIS quasi-state to grow
Condoned Turkish brutality against the Kurds, except where convenient
etc. etc.
And speaking of the Syrian civil war, here is a précis of its economic impacts:
http://www.atlanticcouncil.org/blogs/syriasource/factbox-syria-s-conflict-economy
That's the cost of insisting on regime change diplomatically, or trying to enforce it through intelligence agencies when there's no sign of a popular mandate.
It's not like any of this is unknown, and it's not like it can be fit to either a vision of humanitarian benevolence or even basic realpolitik. It's a clusterfuck of venal strategic meddling that's been non-stop since before WWII.
So that's what imperialism is, anyway, in case you were still wondering. And yes, there's a very long list of what the former Soviet Union got up to in the region as well, but not as long.
As for the US and its struggle with Russia in the contemporary world, you should start with the fact that US military spending exceeds Russian by a factor of ten, and go from there.