United States Defence Secretary, James Mattis has said America still hopes to solve the North Korea crisis using diplomacy. After days of fiery rhetoric from both US and North Korea, Mr Mattis said the war would be "catastrophic" and that diplomacy was gaining results.
Pyongyang on Thursday announced it was finalising a plan to fire four missiles near the US territory of Guam.
Earlier, President Donald Trump said North Korea should be "very, very nervous" if it acted against the US.
He said the regime would be in trouble "like few nations have ever been" if they do not "get their act together".
BBC news reports that tensions have escalated rapidly in recent weeks after North Korea tested two intercontinental ballistic missiles in July.
It was further angered by a subsequent UN decision to increase economic sanctions against it.
Mr Mattis, speaking in California late on Thursday, said it was his job as defence secretary to be ready for conflict.
But he said the diplomatic effort, under Secretary of State Rex Tillerson and UN Ambassador Nikki Haley, "has diplomatic traction, it is gaining diplomatic results".
He did not provide any further details on what diplomatic efforts were under way. However, the UN Security Council agreed on fresh sanctions against North Korea on Saturday.
Mr Mattis said: "The tragedy of war is well enough known. It doesn't need another characterisation beyond the fact that it would be catastrophic."
When asked about US military plans for a potential conflict, Mr Mattis said the country was ready, but "I don't tell the enemy in advance what I'm going to do".