American and Philippine troops began annual war drills with the Asian nation on high alert following a series of bombings blamed on Al Qaeda-linked militants.

About 5,700 U.S. Marines and sailors out of Japan and 1,300 Filipino soldiers were taking part in two weeks of exercises in the northern and southwestern Philippines.

On Sunday, Philippine troops watched Marines aboard CH-53 helicopters insert a team to capture a high-value individual hiding in a building — a scenario that has been put to use during operations in the southern Philippines.

"What we try to do here is make the training as realistic as possible," said U.S. Marine Sgt. Levi Konz, a Special Operations Training Group instructor.

The exercises, which have been credited with giving Filipino troops a crucial edge in battling militants in the restive south, coincided with three bombings in the region last week, including a blast that killed six people and wounded 29.

On Sunday, a small explosion at a police camp on Jolo island wounded two people, and troops dismantled another explosive device just hours before it was timed to go off.

CountryWatch: Philippines

Authorities blamed two Indonesian militants from Al Qaeda-linked Jemaah Islamiyah and their Filipino cohorts from the Abu Sayyaf group — the target of a U.S.-backed offensive on the southern island.

The bombings may be in retaliation for the Oct. 3 arrest of the wife of Dulmatin, one of the Indonesians hiding on Jolo and a key suspect in the 2002 Bali bombings, officials said.

Since 2002, American troops have trained and armed Filipino soldiers battling Muslim militants in the south, which has become a crucial front in the U.S.-led campaign against terrorism because of the reported presence of terror training camps run by Jemaah Islamiyah.