US President Donald Trump says he expects to meet North Korean leader Kim Jong Un again soon as part of efforts to press Pyongyang to give up its nuclear weapons program.
Speaking to reporters at the White House, Mr Trump defended his negotiations with Mr Kim and said he had never emphasized the speed of Pyongyang's denuclearisation.
Mr Kim vowed to work toward denuclearisation of the Korean Peninsula when he met with Mr Trump for the first time at a summit in Singapore in June, but there has been little concrete progress since.
Mr Kim said in a nationally televised New-Year address that he was ready to meet again with Mr Trump anytime but warned he may take a "new path" if US sanctions and pressure against the country continued.
Mr Trump told reporters on Wednesday that he received a great letter from the North Korean leader and that he would love to read it out loud, but did not do so.
South Korea's Chosun Ilbo newspaper reported that Mr Kim had sent a message to Mr Trump regarding the stalled nuclear talks. The report did not include details about the "letter-like" communication.
Mr Trump has said previously that a second summit with Mr Kim was likely in January or February, though he wrote on Twitter last month that he was "in no hurry."
In his address, Mr Kim said denuclearisation was his "firm will" and North Korea had "declared at home and abroad that we would neither make and test nuclear weapons any longer nor use and proliferate them."
However, he warned that North Korea might be "compelled to explore a new path" to defend its sovereignty if the United States "seeks to force something upon us unilaterally ... and remains unchanged in its sanctions and pressure."
Mr Kim's comments have fuelled doubts over whether North Korea intends to give up a nuclear weapons program it has long considered essential to its security.
Analysts said Mr Kim's message sent clear signals that North Korea was willing to stay in talks with Washington and Seoul this year - but on its own terms.
US Secretary of State Mike Pompeo made several trips to Pyongyang last year but the two sides have yet to reschedule an abruptly cancelled November meeting between him and senior North Korean official Kim Yong Chol aimed at paving the way for a second summit.
As well as demanding a lifting of sanctions, Pyongyang has been seeking an official end to the 1950-1953 Korean War in response to its initial, unilateral steps that have included dismantling its only known nuclear testing site and a key missile engine facility.
US officials have said the extent of initial North Korean steps were not confirmed and could be easily reversed.
Washington has halted some large-scale military exercises with South Korea to aid negotiations, but has called for strict global sanctions enforcement until North Korea's full, verifiable denuclearisation.