UN Security Council dispatches peacekeeping forces. US has a vote/veto on the Sec. Council.
"Peacekeeping forces are contributed by member states on a voluntary basis. As of 31 December 2013, the total size of the peacekeeping force is 98,200 police, troops, and military experts. European nations contribute nearly 6,000 units to this total. Pakistan, India, and Bangladesh are among the largest individual contributors with around 8,000 units each. African nations contributed nearly half the total, almost 44,000 units.[8]
Every peacekeeping mission is authorized by the Security Council."
https://en.wikipedia.org/wiki/United_Nations_peacekeeping