"The president has received the letter from Kim Jong Un. It was a very warm, very positive letter," White House spokeswoman Sarah Sanders said, adding that the message showed Pyongyang's "continued commitment to focus on denuclearization" on the Korean Peninsula.

"The primary purpose of the letter was to schedule another meeting with the president, which we are open to and are already in the process of coordinating," she said at the first White House press briefing in nearly three weeks.

Sanders added that the letter was "further evidence of progress" in Washington's relationship with Pyongyang.

Trump and Kim held a historic summit in Singapore in June that raised prospects of a breakthrough on curtailing North Korea's nuclear program.

Despite follow-on negotiations on denuclearizing the peninsula hitting a snag leading to Secretary of State canceling a planned trip to the North late last month, the new letter showed signs that the discussions remain alive after weeks of apparent deadlock.

"We think it's important and we're glad that we're making progress," Sanders said, adding that Trump deserves the "credit" for bringing the two parties to the table.

"At the end of the day, ultimately, it's always going to be best when you can have the two leaders sit down," she added.

The White House has pointed to a series of accomplishments in recent months -- a release of US hostages, the repatriation of war remains believed to be of US service members, a pause in North Korea's missile and nuclear tests, and a recent military parade through Pyongyang that did not show off the country's intercontinental missiles -- to suggest progress between the foes.

Sanders was asked whether the next Trump-Kim meeting would take place in Washington, but she demurred, saying, "we'll let you know when we have further details."