Recently, before Russia offered an alternative France was considering the possibility of a U.N. Security Force.
France holds a permanent seat on the U.N. Security Council and was on board with the USA about striking Syria. They were going to offer a resolution in the Security Council to send in the baby blues.
So this may not be as far fetched as some are lead to believe.
I would like for the US to be part of a security force from the UN. As long as that security force was primarily manned and funded (militarily) by UN members in the Middle East, Northern Africa, and similarly located countries. Countries with a vested interest in regional stability.
Oh, and I'd like Russia to kick in a fair share as well. Would this lead to an imbalance in power? Doubtful, unless the follow-up diplomacy and financial assistance from Russia was both benign and lucrative enough to exceed US government and NGO efforts. Not likely.
While the US often (too often) participates in UN peacekeeping missions, they are ALWAYS under American command. I believe that is US law. I am not aware of any instance of American Combat troops wearing the UN blue beret, especially in modern times, but I may be mistaken. I do not usually speak in absolutes because I may be speaking in error.