Southern Command deputy chief Brig. Gen. Francisco Callelero said two battalions of Army and Marines have been deployed to secure the American troops participating in the "Balikatan" joint military exercises that will begin next month.
US troops began arriving last week in Sulu for the start of the mission.
About 250 US troops, mostly engineers and construction crews, arrived in Sulu in batches.
A calendar of activities released by the Southern Command here showed the Balikatan joint exercises are focused mostly on humanitarian and engineering civic action programs starting Feb. 2 until March 2.
The program will be succeeded with a follow-up engineering and medical mission by the Armed Forces of the Philippines (AFP).
Callelero said the security forces would come from Task Force Comet, a group of soldiers that have been trained by the US Special Forces to go after the remaining Abu Sayyaf who are still holding out in the dense jungles of the island province.
Callelero said the tight security was put in place against possible attacks or harassment from Abu Sayyaf rebels.
"There are reports (of threats by the Abu Sayyaf). But even before the Balikatan, there are already threats from the group," Callelero said. "But we already have plans in place to thwart any impending atrocities," he added.
Callelero said at least two battalions would be utilized for the force protection alone on top of the standby forces that will be immediately deployed for "any eventuality."
The US Joint Special Operation Task Force-Philippines (JSOTF-P) will also provide security as an "inner layer of defense" over the area where the humanitarian and engineering missions will be conducted.
"We are throwing a tight security (net) to ensure the safety of the US team and the civilians because the success of this humanitarian mission is the success also of our residents in Sulu who will benefit most of the program to improve their living conditions," Callelero said. — Roel Pareño