WASHINGTON -- The United States demanded the safe release of two American pilots whose Army scout helicopter strayed into North Korean airspace yesterday and was either shot down or forced to make an emergency landing.
Defense Secretary William J. Perry said in a statement that the Pentagon did not know the condition of the two crew members, although North Korean news agencies reported that the pilots had been taken into custody for questioning.
Leon E. Panetta, the White House chief of staff, expressed "serious concerns" about the welfare of the crew of what the Pentagon said was an unarmed, two-seat OH-58 Kiowa helicopter.
"We want them returned," Mr. Panetta said during a television interview. He added: "It's ominous that this incident took place. This should not have happened."
Mr. Panetta said that the pilots "evidently went into North Korean territory and as they were heading back toward South Korea they were either forced down in an emergency landing or shot down. We do not know at this time what exactly did take place."
North Korea had announced that an "enemy helicopter" had been shot down. But administration officials said it was not clear whether it was shot down or whether the helicopter had been forced down by a mechanical failure.
Senior Pentagon officials said the helicopter was on a routine training mission; they could not explain why the Kiowa flew three to five miles into North Korean territory.
U.S. air crews are trained to be exceptionally careful flying near the 2.5-mile-wide demilitarized zone that divides the Korean Peninsula. Each side of the zone bristles with tanks, artillery and other heavy weapons. North Korea has frequently accused the United States of disguising surveillance operations as training missions.
Administration officials said that Secretary of State Warren M. Christopher spoke by telephone to Rep. Bill Richardson, D-N.M., a member of the House Select Committee on Intelligence, who arrived yesterday in Pyongyang, the North Korean capital, on a previously scheduled visit.
"The congressman reported that his North Korean hosts described the incident as unfortunate and said that it was under investigation," the Pentagon statement said.
Stu Nagurka, a spokesman for Mr. Richardson, said the congressman was scheduled to meet all day today with North Korean officials.
A U.S.-North Korean commission that meets regularly to discuss the status of a formal armistice that was never reached before the end of the Korean war, is also scheduled to meet today.
The crew's fate will be the main subject of both meetings.
State Department officials also contacted North Korea's mission the United Nations and demanded more information on the two crew members, administration officials said.
The South Korean government reported no suspicious military movements in the North or further attempts to score propaganda points.
Kenneth Bacon, the Pentagon spokesman, said that details about the incident yesterday were still sketchy.
But he said that the helicopter took off at 10:04 a.m. local time yesterday from Camp Page, about 50 miles northeast of Seoul, )) for an orientation mission and was scheduled to return at 12:30 p.m.
The helicopter was in radio contact with its base until 10:40 a.m. and landed in North Korea at 11:03 a.m. in Kumgang County, on NorthKorea's east coast.
Mr. Bacon said the air crew was using terrain maps to navigate in its low-altitude flight over the hilly, wooded area in northeastern South Korea. The helicopter was not equipped with a more advanced navigational aid called a global-positioning system.
Radar contact with the helicopter was frequently broken as the helicopter flew in and out of mountain valleys.
North Korea's news agency reported that the helicopter had been brought down "in a self-defensive measure of the anti-air gunners of the Korean People's Army." According to the North Korean account, the helicopter was hit by a single shot.
The Pentagon identified the crewmen as Chief Warrant Officer David Hilemon of Clarksville, Tenn., and Chief Warrant Officer Bobby Hall of Brooksville, Fla.
Both are members of Company A, 4th Battalion, 501st Aviation Regiment.
Each pilot had more than 1,000 hours of flying time in the Kiowa, but it was not clear for how much time the pilots had flown in South Korea.
While Mr. Panetta sought to make clear that the administration was taking the incident seriously, it was not yet causing great alarm within the administration.
Earlier this year, tensions between the United States and North Korea grew to the brink of confrontation over Pyongyang's suspected nuclear weapons program.
But the two nations reached an accord in October calling for North Korea to freeze its nuclear program, allow international inspections and eventually dismantle its remaining nuclear sites.
In exchange, the United States promised to deliver safer nuclear reactors costing $4 billion, and this month cleared most of the obstacles toward opening liaison offices in Washington and in Pyongyang.