U.S. Reconnaissance Plane Crashes in S. Korea; 2 Pilots Reportedly Safe : Asia: Accident occurs four days after Army helicopter went down in the North. Pyongyang still holds surviving officer.

A U.S. reconnaissance airplane developed mechanical trouble and crashed in a rice paddy on South Korea’s west coast today, but the U.S. military command said the two pilots escaped safely.

The RV-1 Mohawk airplane was on a routine training mission before it crashed about 8:30 a.m. near the farming village of Taean, 40 miles south of Osan Air Base located south of Seoul.

U.S. military spokesman Jim Coles could not confirm South Korean news reports that the airplane burst into flames. He said no further details were likely until the command completed its investigation.

The crash came four days after a U.S. Army helicopter drifted across the demilitarized zone and went down in North Korea, killing one of its two pilots.

Coles said there was no connection between the two accidents.

“We run tens of thousands of flights a year and have maybe a dozen accidents,” he said.

Meanwhile, North Korea continued to stonewall U.S. demands for the release of the surviving pilot and remains of the dead one in the North Korean helicopter incident.

The Clinton Administration formally warned North Korea on Tuesday that if it does not quickly release the U.S. Army pilot whose helicopter went down there Saturday, U.S.-North Korean cooperation on nuclear and economic issues may be threatened.

During a meeting with reporters, Secretary of State Warren Christopher said any further delay “would be of great concern to (the United States) and would affect the atmosphere in which we’d been hoping to improve our relations with North Korea.”

If the North Koreans “do act promptly and in a humane way on that subject, it will be conducive to good relations,” he added. “But the other side of the coin, unfortunately, is true as well.”

Christopher’s warning, which the secretary said also was delivered through diplomatic channels to Pyongyang, was the strongest public statement by a high-ranking Administration official about the consequences of not releasing the surviving pilot, as well as the body of his fellow pilot.

President Clinton said Sunday that the co-pilot of the helicopter, Chief Warrant Officer David Hilemon of Clarkesville, Tenn., was killed in the incident, while the pilot, Chief Warrant Officer Bobby Hall of Brooksville, Fla., is still alive.

U.S. officials have said the helicopter, which was unarmed, accidentally strayed while on a routine training mission and edged 11.4 miles north of the border. The Pentagon says it still does not know whether it was shot down or was forced to land because of mechanical failure.

Administration policy-makers took a low-key approach for several days after the incident but began hinting Monday that the broader talks would be jeopardized if Pyongyang did not act soon. Christopher underscored that warning Tuesday.

Top Administration officials had been hoping that relations between the two countries would improve in the face of the broader talks, which have been aimed at patching up a dispute over North Korea’s nuclear weapons program and providing Pyongyang with new aid in exchange.

However, Pyongyang has been slow to meet U.S. demands in the helicopter incident, and Administration policy-makers have become increasingly frustrated.

On Tuesday, North Korean representatives to the U.N. Military Armistice Commission at Panmunjom--one of the three principal conduits for relations between the two governments--agreed to take the U.S. request to their country’s leadership. There has been no reply so far.

However, Christopher said late Tuesday that Rep. Bill Richardson (D-N.M.), who is in Pyongyang and acting as a U.S. envoy, would meet within a few hours with a high-ranking official of the North Korean Foreign Ministry.

The United States also has been pursuing the issue through the North Korean mission at the United Nations in New York, which frequently has served as an informal channel for the broader talks, and through other countries in the region.

U.S. officials conceded privately that, up to a point, they are forced to play a waiting game while Pyongyang tries to make the most of the situation for its own political ends. In the meantime, the North Koreans are keeping the Administration on edge.

The Pentagon already has admitted that the helicopter strayed into North Korean airspace by mistake--an unusual bit of candor designed to win more rapid release of the two pilots. However, U.S. officials so far have declined to apologize for the incursion.

Christopher’s warning was underscored by Winston Lord, assistant secretary of state for East Asian and Pacific affairs, who told reporters that “how this issue is resolved and how soon it is resolved is very important for our bilateral relations with North Korea.”

“We’re engaged in very serious efforts of gaining the crew . . . as well as the helicopter and personal effects,” he said.

Watanabe reported from Seoul, Pine from Washington.