Killed 2 Americans, Philippine Rebels Say; More Deaths Threatened Over Bases : Asia: A dangerous shift in Communist tactics is seen. U.S. negotiators suffer a setback in talks on military installations.

Communist guerrillas claimed responsibility Tuesday for the shooting deaths of two U.S. Air Force enlisted men last Sunday and warned that killings will continue until all American troops and military bases are “kicked out of our country.”

The statement by the New People’s Army, the armed wing of the outlawed Philippine Communist Party, said the two American airmen were “punished” in retaliation for U.S. support of Philippine counterinsurgency efforts.

“This incident serves as a warning to the U.S. government and its local puppet regime,” the statement said. “We will not stop until abuses by American officers and soldiers have ceased. We will not stop until all U.S. bases and all American occupation soldiers are kicked out of our country.”

Analysts here said the statement indicated a dangerous shift in strategy for the 21-year-old Communist insurgency. They said it gives formal warning for the first time that any U.S. service personnel are now a potential target for assassination. Until now, the NPA had only acknowledged targeting ranking U.S. officers, intelligence agents and counterinsurgency specialists.

“It means it’s open season on Americans at the bases,” said one Western diplomat who analyzes the rebel movement. “It really turns the heat up.”

The warning came as U.S. negotiators suffered a setback on the first day of substantive talks with the Philippine government over the future of Clark Air Base, Subic Bay Naval Base and four smaller U.S. military facilities here.

In a surprise move, Philippine negotiators formally notified the United States that the installations must be closed by September, 1991, if no new lease agreement is reached. The United States has long interpreted existing base accords to give it until September, 1992, a full year later, to dismantle the installations.

Both sides agreed that the Philippine “termination notice” does not preclude new leases. But unless a new agreement is reached quickly, the Pentagon may be forced to start cutting military operations and personnel here as early as this fall to meet the 1991 deadline, officials said.

“At this point, we’re still concerned with trying to avoid that inevitability,” said Stanley Schrager, spokesman for the U.S. negotiating team. “Our view is we don’t want this to become a major obstacle. We hope we’ll be able to avoid conflict on this issue.”

The deadline clearly adds pressure, however, since President Corazon Aquino’s government says the Philippine constitution of 1987 requires a formal treaty for any new base accord. A full treaty would require ratification by the Philippine and U.S. senates.

The termination notice was delivered without warning to President Bush’s special negotiator, Richard L. Armitage, Schrager said. The United States hopes that the so-called exploratory talks, expected to end Friday, will lead to formal negotiations on extending or modifying the leases.

There were some indications that the termination notice was designed to show Manila’s independence and to blunt charges by opponents of the bases that Aquino has caved in by even agreeing to talk about them.

“We have taken that first step in terminating an agreement that was executed in 1947 during the days of lingering U.S. colonialism in the Philippines,” Philippine spokesman Rafael Alunan III told reporters.

The Pentagon has 40,000 service personnel, civilian contractors and family dependents in the Philippines. Thousands of others arrive on temporary duty, however, including the two airmen killed outside Clark Air Base last weekend.

John H. Raven, 19, of Delta Junction, Alaska, and James C. Green, 20, of Craig, Colo., were assigned to Kunsan Air Base in South Korea.

The Communist rebel statement, which was signed by Jay-ar Sigua, regional NPA spokesman for central Luzon, did not mention a third U.S. serviceman, Marine Sgt. John S. Fredette, 34, of Buena Park, Calif., who was shot to death outside Subic Bay on May 4. U.S. officials suspect a separate NPA group in that death.

The new NPA policy poses major problems for security, officials conceded, since up to half the resident U.S. forces, and many of the visitors, live off base. They are now under orders to restrict all off-base travel, use a buddy system or travel in groups. All others are confined to the bases, and off-post leave has been canceled.

In the statement, the NPA accused the United States of participating in Philippine military “interrogation and torture” of suspected guerrillas and “countless abuses” against Filipino base workers, women and nearby residents. A U.S. Embassy spokesman declined to comment.