NATO on Alert Against Bosnia Terrorist Attack

International peacekeepers in Bosnia--including thousands of U.S. troops--were put on heightened alert Tuesday after indications that they may be the targets of terrorist acts such as car-bombings, U.S. officials said.

Defense Department officials said the threats were discovered as a result of intercepted communications and other evidence.

They said suspicious individuals have been conducting surveillance of U.S. military sites in Bosnia-Herzegovina recently and sometimes have taken photographs.

While declining to provide details, Pentagon spokesman Kenneth H. Bacon said the reports provided by intelligence sources constitute “a threat we take seriously.”

Officials later said those threats included the possibility of car-bomb attacks against NATO forces, including Americans.

U.S. officials said American commanders have increased security around U.S. installations in Bosnia with such measures as stepped-up patrols, more checkpoints and more intense questioning of anyone caught prowling around North Atlantic Treaty Organization installations.

The action follows a weekend during which NATO forces in the Serb-controlled section of Bosnia were ordered on full alert in preparation for possible military action if the Serbs did not allow peacekeepers to inspect an arms cache at a Serbian military base at Han Pijesak.

On Monday, the Serbs relented and agreed to let NATO-led forces enter the base.

Cheered by what they called the “successful ultimatum” that forced Bosnian Serbs to open the disputed military site, U.S. and NATO leaders vowed Tuesday to prevent a spate of weapons violations from derailing the peace accord brokered in Dayton, Ohio.

NATO Secretary-General Javier Solana, talking to reporters after a meeting in Geneva with Secretary of State Warren Christopher, said the NATO-led international military force’s inspection of the Han Pijesak site dramatized the alliance’s determination to prevent violations of the peace agreement.

The Pentagon has been especially sensitive to the threat of terrorism since a June 25 truck-bombing at a housing complex for American military personnel in Dhahran, Saudi Arabia, killed 19 U.S. airmen.

Investigators still have not determined who was responsible for the bombing. The Pentagon has begun moving U.S. military personnel and equipment to a more isolated air base 60 miles southeast of Riyadh, the Saudi capital.

Officials said the heightened security imposed Tuesday in Bosnia was mainly to deal with threats from Iranian-backed Islamic militants.

The Clinton administration has certified that the thousands of Islamic militiamen who fought with the Bosnian Muslims before the signing of the Dayton peace accord have been largely expelled from the area, but some still remain--possibly under Iranian influence.

U.S. officials have been saying that Iran has been stepping up its support of terrorist activities against U.S. facilities around the world.

Pine reported from Washington and Kempster from Geneva.