Here are a few examples: - Japan and Korea were historically enemies. But they've been at peace since WWII, mainly because both have US troops stationed there.

Here are a few examples: - Japan and Korea were historically enemies. But they've been at peace since WWII, mainly because both have US troops stationed there. Any time tensions flare up, the US does a little diplomacy and they make nice. That will probably continue for a while, even without US troops because both countries value the alliance with the US and don't want to be dominated by China. - With the US withdrawing from the Middle East, Saudi Arabia is arming its self and allying with Israel (!) to deal with the threat from Iran. Iran, meanwhile is emboldened to attack Saudi oil fields and threaten shipping through the Persian Gulf. Meanwhile Yemen has destabilized, leaving Saudi Arabi to worry about whether it will be able to get access to the Arabian Sea. Hard to predict how this shakes out, but I can't see it being peaceful and stable. - As soon as the US showed signs of disinterest in Europe, Russia annexed Crimea. With that experiment having been successful, they'll be looking for more opportunities to take back bits of the USSR. Now Europe is arming up to protect themselves from that threat. The catch is that Europe needs oil and natural gas, and that's mainly coming from Russia right now. We may see internal conflict in Europe over whether to be friendlier to Russia to secure that supply, and perhaps increased European presence in the Middle East. Either way, stability in that part of the world has decreased without US willingness to commit troops and money to maintaining it.