WASHINGTON (AP) _ The United States demanded the release of two U.S. Army airmen whose helicopter crossed into North Korean airspace Saturday and was either shot down or forced to land. The White House called the incident ''ominous.''

''We're talking with North Korea,'' Jim Coles, a U.S. military command spokesman, said early Sunday in Seoul, South Korea.

Even though the United States and North Korea do not have diplomatic relations, Coles said talks were being conducted through military and diplomatic channels.

''We're still talking with the North Koreans, trying to get them to come to the table,'' said Coles. ''We're trying to get a meeting set up through UNMAC (the U.N. Military Armistice Commission).''

More than 24 hours after North Korea announced it had shot down an ''enemy'' helicopter that violated its airspace, Clinton administration officials said they could not determine the condition of the two American airmen.

In fact, there was no independent confirmation that the missing men were actually in North Korean custody even though their chopper was seen going down in rugged North Korean territory within sight of the DMZ.

A leading South Korean national daily, Dong-A Ilbo, disputed the North Korean assertion that it shot down the helicoper. It cited South Korean military sources as saying no signs of a pursuit or attack were evident after the chopper was seen disappearing into North Korean airspace by South Korean ground troops patrolling the eastern sector of the demilitarized zone.

Coles said a navigational mistake could be one factor in the incident, noting that a recent heavy snowfall, first of the winter, made landmarks hard to distinguish in the mountainous terrain. But technical troubles and other mishaps could not be ruled out, he said.

The Pentagon identified the men as Chief Warrant Officer David Hilemon of Clarksville, Tenn., and Chief Warrant Officer Bobby Hall of Brooksville, Fla. Both are members of A Company, 4th Battalion, 501st Aviation Regiment at Camp Page in South Korea.

''We want them returned,'' Leon Panetta, the White House chief of staff, said on CNN. ''It's ominous that this incident took place. This should not have happened.''

Rep. Bill Richardson, who coincidentally is in North Korea on behalf of the House Intelligence Committee, requested immediate access to the crewmen, his spokesman, Stuart Nagurka, said.

Nagurka, who was being contacted by telphone by Richardson, said the New Mexico Democrat has had three meetings with North Korean officials in which he asked to meet with the servicemen and offered to extend his stay in hopes of being able to escort them out of North Korea.

He said late Saturday that Richardson was continuing to meet with the North Koreans.

Richardson, who is in contact with Secretary of State Warren Christopher, ''stressed that failure to aggressively investigate this case, and failure to return the missing servicemen, would have a serious impact on U.S.-North Korean relations,'' Nagurka said.

The lawmaker ''has asked to urgently meet with military officials to discuss this case and has canceled all other discussions which were to have concentrated on the U.S., North Korean nuclear agreement,'' the spokesman added.

Even though there are no formal diplomatic relations with North Korea, although U.S. and North Korean officials recently began moving toward establishing liaison offices in each other's capital as part of a breakthrough agreement in October on the future of North Korea's nuclear program.

U.S.-North Korea relations were especially tense during lengthy negotiations over the nuclear program. At times, U.S. officials worried that the north might consider launching a military strike at the south, although in recent months there had been no indications of increased tensions along the border.

The incident comes at sensitive period for the North Korean leadership. Kim Jong Il is said to be in charge, but Korea-watchers say it remains unclear whether he has full control. He is the son of Kim Il Sung, who founded the communist state in the 1940s and ran it until his death last summer.

Panetta said U.S. officials did not yet know exactly where the men were being held. He said their helicopter had strayed ''anywhere from five to perhaps as much as eight kilometers'' (three to five miles) into North Korean territory.

''We do not know at this point why that happened,'' Panetta said.

In a written statement, Defense Secretary William Perry said their OH-58C Kiowa Warrior, an unarmed reconnaissance helicopter, ''strayed'' into North Korean airspace and went down along an eastern section of the demilitarized zone.

The DMZ is a heavily fortified buffer zone that has separated the north and south since the Korean War ended in 1953. U.S. forces, currently numbering about 37,000, have helped South Korean armed forces patrol the area ever since.

''It is unclear whether the helicopter made an emergency landing or was shot down,'' Perry said. ''At this time, the condition of the two-man crew is not known.''

The State Department also contacted the North Korean mission at the United Nations in New York on Saturday ''to insist on the urgency of information on the incident, as well as for prompt access to the crew,'' Perry said.

The defense secretary said the Pentagon had received conflicting information about the incident and thus could not provide a full explanation of it.

Hours later in St. Louis, Perry said he still had little firm information but told reporters the U.S. chopper ''was clearly where it should not have been'' when it went down.

''As I stand here, I don't know the answer to that and I don't care to speculate,'' he said. ''Quite evidently, the pilots became disoriented and wandered over the border.''

Perry meet with reporters shortly before addressing about 2,000 veterans gathered to commemorate the 50th anniversary of the Battle of the Bulge.

Other U.S. defense officials, speaking on condition of anonymity, said one of the two airmen is experienced at flying in the vicinity of the demilitarized zone, which is a 2.5-mile-wide strip separating North and South Korea.

The other pilot was a newcomer and was on the flight to become familiar with the mountainous terrain.

Weather was not a factor in the incident, one Pentagon official said.

U.S. helicopters routinely fly in the vicinity of the demilitarized zone but do not enter it on the North Korean side. The aircraft involved in this incident, an OH-58C Kiowa Warrior, was a reconnaissance aircraft often used as a utility aircraft for scouting and training. An armed version of the Kiowa Warrior, designated the OH-58D, is usually the choice for reconnaissance missions.

Military incidents in recent years have become rare along the 155-mile DMZ. Nevertheless, some 2 million troops are stationed along the line, which stretches on a zigzag from the Sea of Japan in the east to the Yellow Sea in the west.