President Donald Trump (R) gestures as he meets with North Korea's leader Kim Jong Un (L) at the start of their historic US-North Korea summit, at the Capella Hotel on Sentosa island in Singapore on June 12, 2018.

Almost all of the immediate results from the summit between President Donald Trumpand North Korean leader Kim Jong Un are governed by uncertainty, experts say, including whether the U.S. will renege on its commitments to protect allies like South Korea and Japan, whether China has the ability to help maintain peace in the region, and perhaps most of all whether Pyongyang will back away from a nuclear weapons program that puts the entire world at risk.