Rex Tillerson has warned North Korea that refusing to negotiate on the surrender of its nuclear arsenal could trigger a military response from the US.
After a meeting about furthering sanctions against the rogue nation, the secretary of state said the White House wants a diplomatic solution to the nuclear standoff, but Pyongyang has not been a "credible negotiating partner."
US-North Korea talks would need a "sustained cessation" of missile tests, he added.
Tillerson declined to comment on whether Trump is considering a preemptive strike against Pyongyang, in response to reports that some in the administration advocate military action to give the North a "bloody nose".
"We all need to be very sober and clear-eyed about the current situation," Tillerson said when asked about the possibility of a war.
He said North Korea has continued to make significant advances in its nuclear weapons through the thermonuclear test and progress in its intercontinental missile systems.
"We have to recognise that the threat is growing and that if North Korea does not choose the pathway of engagement, discussion, negotiation then they themselves will trigger an option," he said.
His uncompromising message came after a gathering in Vancouver of 20 nations that were on America's side during the Korean War, where there was scepticism among the allies over North Korea's sincerity in its recent diplomatic opening with the US-allied South.
Despite Washington's tough stance and determination to keep up the pressure on North Korea, president Donald Trump has signalled openness to talks with the North under the right circumstances.
After months of insults and blood-curdling threats which he has traded with North Korean leader Kim Jong Un, Trump suggested in an interview last week that the two leaders could have a positive relationship.
Tillerson declined to say on Tuesday whether Trump has spoken directly to Kim.
"I don't think it's useful to comment" he said.
"We are at a very tenuous stage in terms of how far North Korea has taken their program and what we can do to convince them to take an alternative path. And so when we get into who's talking to who and what was said, if we want that to be made known or made public we will announce it."