Senior US national security officials have said a military confrontation with North Korea is not imminent, but they cautioned that the possibility of war is greater than it was a decade ago.
CIA director Mike Pompeo and HR McMaster, Donald Trump's national security adviser, tried to provide assurances that a conflict is avoidable, while also supporting the president's tough talk.
They said the United States and its allies can no longer afford to stand by as North Korea pushes ahead with the development of a nuclear-tipped intercontinental ballistic missile.
"We're not closer to war than a week ago but we are closer to war than we were a decade ago," Mr McMaster said, adding that the Trump administration is prepared to deal militarily with North Korea if necessary.
But he stressed the US is pursuing "a very determined diplomatic effort" led by Secretary of State Rex Tillerson that is coupled with new financial sanctions to dissuade North Korean leader Kim Jong Un from further provocations.
"The US military is locked and loaded every day," Mr McMaster said, repeating Mr Trump's threat.
Mr Pompeo said "there's nothing imminent today", in response to a question about how worried people should be over the escalating tensions.
He said the US has a "pretty good idea" of North Korea's intentions, but he declined to provide specifics.
The CIA chief described Mr Kim as "rational" and responsive to "adverse circumstances".
He added: "The reaction in North Korea that we are intending to get is an understanding that America is no longer going to have the strategic patience that it's had that has permitted him to continue to develop his weapons programme. It's that straightforward."
Meanwhile, top US military officer General Joseph Dunford is in Asia and is expected to meet with leaders in South Korea, Japan and China.
Gen Dunford, the chairman of the Joint Chiefs of Staff, told reporters travelling with him that he aims to "sense what the temperature is in the region".
He also will discuss military options in the event the "diplomatic and economic pressurisation campaign" fails.
"We're all looking to get out of this situation without a war," he added.