During a press briefing, White House press secretary Sarah Sanders called the letter as 'warm' and 'positive'.

"Yeah, the President has received the letter from Kim Jong Un. It was a very warm, very positive letter. We won’t release the full letter unless the North Korean leader agrees that we should," Sanders said.

She said the US is 'open' to a second summit.

She said: "The primary purpose of the letter was to request and look to schedule another meeting with the President, which we are open to and are already in the process of coordinating that."

Trump and Kim had met for the first time on June 12 in Singapore.

2017 witnessed US President Donald Trump slamming North Korean leader Kim Jong-un as the Asian nation continued to conduct several of its missile tests, teasing world peace and tranquillity and often threatening to trigger a war.

The situation became far tensed when North Korea tested an inter-continental ballistic missile (ICBM) that the nation said was capable of striking the US mainland.

The United Nations Security Council imposed strong new sanctions against the Asian nation after its Nov 29 launch of a nuclear-capable weapon.

Trump and North Korea continued to exchange barbs earlier this year too.

Image: Donald Trump/Twitter