President Donald Trump and North Korean leader Kim Jong-un shared a historic handshake when they met for the first time.

It's the first-ever meeting between a sitting US president and North Korean leader.

Trump and Kim arrived not long ago on Singapore's Sentosa Island, the site of their unprecedented summit. It's aimed at settling a standoff over Pyongyang's nuclear arsenal.

President Donald Trump and North Korean leader Kim Jong-un have signed what Trump says is a "very important" and "pretty comprehensive" document, but refused to tell reporters what the declaration says.

"Both sides are going to be impressed with the result," he added.

Kim told reporters that "the world will see a major change," though it's unclear how.