U.S. Air Force interpreter Tech. Sgt. Paul Shoop, left, works on his computer, as Russian Air Force Col. Alexander Vasiliev sits across the aisle as they fly aboard a civilian airplane playing the role of a hijacked airliner Sunday. The exercise is a first-of-its-kind joint exercise between the United States and Russia to test their coordinated response to a potential international hijacking.

Over the Pacific Ocean ? In a historic first for Cold War adversaries, U.S., Canadian and Russian military officers directed fighter jets and ground controllers to test how well they could track an international terrorist hi-jacking over the Pacific Ocean.

A chartered American jet code-named Fencing 1220 sent a mock distress signal shortly after taking off from Anchorage, Alaska, on Sunday, triggering a pursuit by at least seven fighters and a flurry of radio and telephone calls between military and civilian officials on both sides of the Pacific.

The Associated Press had exclusive access to Fencing 1220, a plush executive-style Gulfstream whose passengers included a Russian Air Force colonel and a senior commander of the North American Aerospace Defense Command, the joint U.S.-Canadian command that patrols the skies over North America.

Their goal: To ensure that two militaries still distrustful of each other can work effectively tackling a terror threat that worries both nations.

One question that arose Sunday was just how much information they need — from the ground, from the fighters, from the hijacked pilots and from the terrorists — and whether fewer, simpler messages might be better than the flood of communication the exercise generated.

Canadian Forces Col. Todd Balfe, the deputy commander of NORAD’s Alaska region, acknowledged it may seem “incongruous” that the exercise was taking place amid tension between his country and Russia over recent Russian bomber flights probing the northern boundaries of Canadian airspace. But with al-Qaida at the front of North American minds and Russia dealing with threats from Chechen rebels, terrorism transcends national boundaries, and exercises like this could lay the foundation for cooperating on other issues as well, Balfe said.

“So we’ll start out with this mission, and if that leads into other missions, for example, probing of air spaces, well, that would be a great thing as well,” he said.

Even veteran officers aboard the Gulfstream were struck by the unprecedented cooperation the exercise required and the breathtaking sight of fighter jets so near that the pilots’ helmets were clearly silhouetted against the bright blue sky.

“I’m kind of in awe,” said U.S. Army Maj. Michael Humphreys, the senior American officer on Fencing 1220 and a spokesman for NORAD. “It was a remarkably well-planned and well-executed exercise.”

It is only half over. The plane will fly back to Alaska later this week, again pursued by fighter jets and tracked by controllers on the ground and in the air.

Russian Air Force Col. Alexander Vasiliev said he knew the day would come when the former Cold War enemies would work in concert, but “he never thought it would be him sitting on the aircraft,” his translator said. Vasiliev declined to be quoted directly, saying he would leave that to a Russian spokesman at a news conference planned later in the week.