WASHINGTON (AFP) - The White House on Wednesday told North Korea to stop making threats after the isolated state dramatically upped its warlike rhetoric and said it had approved nuclear strikes on the United States.

"We've seen today's statement by North Korea, again making unhelpful and unconstructive threats," said National Security Council spokeswoman Caitlin Hayden.

"It is yet another offering in a long line of provocative statements that only serve to further isolate North Korea from the rest of the international community and undermine its goal of economic development.

"North Korea should stop its provocative threats and instead concentrate on abiding by its international obligations."

Earlier, in a statement published by KCNA, the state news agency, the Korean People's Army general staff warned Washington that US threats would be "smashed by... cutting-edge smaller, lighter and diversified nuclear strike means".

"The merciless operation of our revolutionary armed forces in this regard has been finally examined and ratified," the statement said.

Last month, North Korea threatened a "pre-emptive" nuclear strike against the United States, and last week its supreme army command ordered strategic rocket units to combat status.

Pyongyang has successfully carried out nuclear tests, but most experts think the communist state is not yet capable of mounting a device on a ballistic missile capable of striking US bases or territory.