U.S. President Donald Trump and North Korean leader Kim Jong-un concluded a historic summit in Singapore on Tuesday with an unscheduled signing of a document committing their countries to building "a lasting and stable peace regime on the Korean peninsula."

Pyongyang pledged to work "toward complete denuclearization of the Korean peninsula," while Washington would "provide security guarantees," the document said. The U.S. and North Korea would also work together toward "recovering POW/MIA remains."

However, the communique lacked specifics or concrete measures showing how the goals would be achieved. Analysts noted that many of the pledges had been made by both countries in the past and that the rhetoric was similar to previous declarations.

"It's very comprehensive. It's going to happen," Trump told reporters afterward, saying he was sure Kim would follow through. But he added later: "I may be wrong. I may stand before you in six months and say, 'Hey, I was wrong.' I don't know that I'll ever admit that, but I'll find some kind of an excuse."