Four North Korean fighter jets intercepted a U.S. Air Force reconnaissance plane in international airspace over the Sea of Japan on Sunday and came within 50 feet of the big American jet while shadowing it, the Pentagon said on Monday.
Two advanced MiG-29 fighters and two others believed to be MiG-23s intercepted the sophisticated four-engine RC-135 reconnaissance aircraft 150 miles off the coast of North Korea and shadowed the American jet for about 20 minutes, said Navy Lt. Cmdr. Jeff Davis, a Pentagon spokesman.

Senior U.S. officials said Washington would formally protest the incident, once the best means for such a move had been determined. North Korea and the United States do not have diplomatic relations.

Another official said the United States was in "close consultation" with South Korea and other allies about the incident and how to lodge a protest.

The incident came as tension continued to rise on the Korean peninsula over the North's suspected nuclear arms ambitions, and as the United States builds up military forces in the Gulf in preparation for a possible invasion of Iraq.

A North Korean fighter jet also flew briefly into South Korean airspace last week.

South Korea Vows to Work for Peaceful End of Crisis

North Korea on Saturday accused the United States of stepping up spy flights as a preparation for war as South Korea's new president vowed to work for a swift, peaceful end to the nuclear crisis on the peninsula.

Pyongyang had earlier complained that a U.S. RC-135 aircraft had been flying repeated sorties inside its airspace.

Tension over North Korea's suspected nuclear weapons plans rose recently after Washington, citing satellite photographs, said North Korean scientists had fired up a reactor mothballed since 1994 at the Yongbyon complex north of Pyongyang.

PHOTO CAPTION

A RC-135 U.S. reconnaissance aircraft is shown in this undated military handout. Four North Korean warplanes intercepted a US RC-135. (Greg Davis/U.S.A.F via Re