(Photo: Reuters) 

US President Donald Trump on Tuesday expressed optimism that the denuclearization process on the Korean Peninsula would "start soon" and hopes that China could participate in the signing process of a peace treaty.

At a press conference at the Capella Hotel in Singapore's Sentosa Island Tuesday afternoon, Trump called his meeting with North Korean leader Kim Jong Un, "honest, direct, and productive."

Kim has "reaffirmed his unwavering commitment to complete denuclearization of the Korean Peninsula," Trump said, adding that the denuclearization process will start "right away."

"We will do it as fast as it can mechanically and physically be done," he said.

However, Trump also said denuclearization will take time.

According to the president, the US side will meet next week to "go over the details." He also wants to work with China, South Korea and Japan. "China is very helpful," Trump said.

He said at present, sanctions against the North Korea remain, but he looks forward to ending the sanctions if relations progress.

As for a peace treaty in replacement of the current armistice agreement after the 1950-53 Korean War, Trump said he very much wants China to participate in its signing.

"I think it would be great to have China involved and also of course, South Korea," he said.

When asked about establishing diplomatic ties between the United States and North Korea, the president said "hopefully soon" but it's still "a bit early for that."

Kim and Trump held the summit here on Tuesday morning, and signed a joint statement at noon.

In the joint statement, North Korea and the United States said they would commit to establishing a new relationship, and that North Korea would work toward complete denuclearization of the Korean Peninsula.

Both sides said they are committed to jointly building a lasting and stable peace regime on the peninsula, and to recovering the remains of prisoners of war and those missing in action from the Korean War.