SEOUL, South Korea — South Korean airlines are rerouting their flights away from North Korean airspace, hours after the North threatened Seoul's passenger planes amid heightened tensions on the divided peninsula.

The move — which will cost carriers thousands of dollars on each flight — comes after Pyongyang warned in state-run media that it cannot guarantee security for South Korean civil airplanes flying near its airspace and accused the U.S. and South Korea of attempting to provoke a nuclear war with the upcoming joint military drills.

It did not say what kind of danger South Korean planes would face or whether the threat meant the North would shoot down planes.

South Korea has urged the North to immediately retract the threat.

North Korea announced last week that it is preparing to send a communications satellite into space but regional powers suspect the claim is a cover for the launch of a long-range missile capable of reaching Alaska.

The United Nations Command, the U.S.-led body overseeing the 1953 armistice that ended fighting in the three-year Korean War, called the North's threat to South Korean planes "entirely inappropriate."