US Secretary of State Mike Pompeo met on Thursday (May 31) with the the North Korean president's right-hand man to try to salvage next month's summit.
General Kim Yong-chol travelled to New York to discuss the historic meeting between Donald Trump and Kim Jong-un set for June 12th.
"This is a difficult challenge," Pompeo said at a press conference after the meeting. "Make no mistake about it there remains a great deal of work to do and we made progress here, as well as at the same time made progress in the other venues that conversations were taking place. We had all the time we needed today to make the progress that was achievable during our time here in New York City."
General Kim Yong-chol is the most senior North Korean to visit the US in nearly 20 years.
He left the meeting to deliver a letter to President Trump.
"A letter is going to be delivered to me from Kim Jong Un," Trump told reporters. "So, I look forward to seeing what's in the letter, but it's very important to them. So, they'll be probably coming down to Washington, DC, on Friday for the delivery of a letter. I look forward to that."
Meanwhile, Russia's Foreign Minister has visited Pyongyang for the first time.
Sergei Lavrov invited North Korean leader Kim Jong-un to Russia, indicating diplomatic manoeuvres are well underway, 12 days out from the potential summit.