The Pentagon has committed 650 soldiers, including 160 Special Forces troops, to help the Philippine government track down and defeat the ruthless Abu Sayyaf, a gang of Islamic kidnappers that may have links to Osama bin Laden.
Balikatan, formally launched Thursday, is billed as a military exercise to train Philippine soldiers, but these will be no ordinary war games. U.S. troops will carry live ammunition and accompany Philippine forces into the field as they hunt down the Abu Sayyaf. The Americans will remain for at least six months, and their stay could be extended to a year.
A yearlong military exercise in a combat zone might have been unprecedented before Sept. 11, but the attack on the United States has changed the way armies must work together, said Roilo Golez, Philippine President Gloria Macapagal Arroyo's national security advisor.
"We cannot talk in terms of pre-9/11 precedents now," Golez said in an interview. "The concept of war is different when it comes to international terrorism. Faceless enemies, different strategies, different agenda, different weapons, different targets.
"And in the case of Abu Sayyaf, they have a different approach in terrorizing the world. All Americans are targets."
Golez said fears of the United States getting stuck again in Southeast Asia in a conflict like the Vietnam War are unfounded. In the Philippines, he noted, the opposition is not a nation with a well-organized army but a band of rebels numbering in the hundreds.
The joint exercise began against the backdrop of the recent discovery of a Southeast Asian terrorist group affiliated with bin Laden's al-Qaida network. But investigators here have found no link between the Abu Sayyaf and the group, Jemaah Islamiah, which has been operating in the Philippines, Singapore, Malaysia and Indonesia.
In Manila, a scuffle broke out between police and about 50 people demonstrating in front of the U.S. Embassy in the latest of small, almost daily protests against the training exercise. Police made no arrests.
U.S. and Philippine officials launched the exercise in the Philippine city of Zamboanga with a joint ceremony at the army's heavily guarded southern command headquarters.
"We are here to launch a round of exercises and training designed to enhance the capabilities of both of our armed forces and to help the armed forces of the Philippines hone their skills to eliminate the Abu Sayyaf scourge," acting U.S. Ambassador Robert Fitts said.
More than 100 U.S. troops have arrived so far, with the remainder expected in the next few weeks. The United States has also shipped helicopters and new weaponry to the region to supplement the Philippine army's outdated equipment.
The Bush administration, seeking to broaden its war on terrorism, selected the Philippines as its next target in the hope of quashing the Abu Sayyaf, which is holding two U.S. missionaries and a Philippine nurse hostage.
The arrival of U.S. forces has touched off a heated debate over whether the use of American troops in a combat situation should be considered a military exercise.
Some consider the joint operation a transparent attempt to circumvent the Philippines' constitution.
The Philippines evicted the U.S. military from its bases here 10 years ago, and the nation's constitution prohibits foreign troops from operating on the soil of the former U.S. colony. However, the constitution allows for military exercises staged under a treaty with a foreign country.
Arroyo has welcomed Washington's help in defeating the Abu Sayyaf, whose ability to outwit government forces has been a continuing source of embarrassment.
The Philippine military has been trying for much of the last year to crush the Abu Sayyaf, which has kidnapped dozens of people from resorts in the country and in neighboring Malaysia and held them for millions of dollars in ransom.
The group seized Kansas missionaries Gracia and Martin Burnham in May from a seafront hotel on the Philippine island of Palawan, where the couple were celebrating their 18th wedding anniversary. The kidnappers took them by speedboat 300 miles to the island of Basilan, where the Abu Sayyaf is thought to still be holding them in the dense jungle.