WASHINGTON (AFP) - The United States (US) is taking "all the necessary precautions" in the face of escalating threats from North Korea, White House spokesman Jay Carney said on Thursday.

"What we're seeing now is a familiar pattern of behaviour out of North Korea - regrettable but familiar," Mr Carney said aboard Air Force One as President Barack Obama returned to Washington from a fundraising trip in California.

North Korea, incensed at fresh United Nations sanctions and US-South Korea military drills, has issued a series of apocalyptic threats of nuclear war in recent weeks.

Pyongyang's armed forces said earlier they had received final approval for military action against the US, possibly involving atomic weapons.

But while the barrage of threats from the communist North was familiar, Mr Carney said it was nevertheless "obviously a concern", adding: "We're taking all the necessary precautions".

"We're monitoring both the actions taken by and the statements made by the North Korean leadership. And we're also taking prudent measures to respond to that activity and to those statements," the spokesman said.

He said such "action and provocative rhetoric only serve to further isolate North Korea, to harm the North Korean economy, to set back any efforts the North Koreans might want to take towards rejoining the community of nations."

Mr Carney, however, reiterated that Pyongyang "has a path available to it if it seeks to improve its economy and work towards abiding to its international obligations".