America's top diplomat has acknowledged the US is in "direct contact" with North Korea.
Rex Tillerson said Washington was "probing" the possibility of more formal talks, and that "lines of communications" in use with Pyongyang.
"Stay tuned," he added.
It is the first confirmation that backchannel discussions have been taking place, as Donald Trump and North Korean leader Kim Jong Un's heated rhetoric has sparked fears of military conflict.
The war of words centres on North Korea's nuclear ambitions, with the US hoping to force Pyonyang to abandon it nuclear missile tests.
Mr Trump has said the US is "totally prepared" for military action against North Korea, although he has also stressed it is not his preferred option.
Mr Tillerson's comments come during a visit China.
The secretary of state's is holding discussions focused on trade and North Korea, along with preparations for an anticipated visit by President Donald Trump in November.
Chinese foreign ministry spokesman Lu Kang said on Friday that talks would center on "issues regarding the improvement of bilateral ties, President Trump's visit to China within the year as invited by [China#'s] President Xi, and international and regional issues of common concerns."