U.S. President Donald Trump and North Korean leader Kim Jong Un on Tuesday signed a document following their first summit in Singapore, with Trump hailing it as "comprehensive" and Kim saying "the world will see a major change."

Trump, sitting next to Kim in a signing ceremony held after their talks, said he is expecting North Korea's denuclearization process to start "very quickly," without elaborating. He also said he will "absolutely" invite Kim to the White House.

(Kevin Lim/THE STRAITS TIMES/Handout)

Underscoring the amicable mood between the two leaders, Trump said he developed a "very special bond" with Kim and the relationship between the two countries has become "very much different" from before.

Kim said North Korea and the United States have decided to "leave the past behind."