The joint military training exercise dubbed Balikatan 02-1 is set to officially end on July 31.
Maj. Cynthia Terramae, spokeswoman for the US Joint Task Force 510, said the first batch to leave consisted of the Seabees based at Camp Johnson Jadjuli, about five kilometers away from Maluso town in Basilan.
But a Seabees team will stay until July 31 to oversee completion of some projects still under construction.
Among the infrastructure projects implemented by the US military engineers with the assistance of local troops included three bridges and access roads in Mahayahay town and rehabilitation of a port in Maluso.
The Seabees also set up a power-driven deep well pump that provided potable water for residents of Maluso.
Terramae declined to say when the 160 US Special Forces advising and training Filipino soldiers in anti-terrorism will be pulled out.
"The US Special Forces will be at the company level until July 31," Terramae said.
She reiterated that US troops will not take part in actual combat, but are allowed to fire back if attacked.
"We are always ready to defend ourselves... that is why we have this force protection," Terramae said.
Meanwhile, plans are afoot for US military training of two more Philippine special forces unit and instruct eight additional Philippine Army battalions.
The Washington Post, quoting Pentagon officials, said the new security assistance plan represented the next phase of a joint maneuver between the two countries.
The initial phase of the counter-terrorism program, which lasted six months and involved 1,600 US soldiers training over 5,000 Philippine troops running after Abu Sayyaf bandits, is due to wind down on July 31.
The Abu Sayyaf was believed to have suffered a major blow with the killing last month of one of its key leaders, Aldam Tilao alias Abu Sabaya.
The US deployment is Basilan and nearby Zamboanga City was the largest of its kind, after Afghanistan, in Washington’s global war against terrorism.
A Pentagon official said the next phase of US involvement would include fewer US troops and avoid targeting a specific enemy.
Instead of focusing on a particular island, the new training will be directed at Philippine troops spread over several locations, the Pentagon source said.
About 900 US troops will be withdrawn shortly after the current Balikatan ends this month. By October, fewer than 100 will remain, mostly comprising a liaison group in Zamboanga, the unidentified official said.
Next year, US military instructors are slated to return to train two Light Reaction Companies — elite 90-man units that specialize in hostage rescue and other advanced tactical operations.
American troops have trained one such Philippine unit at Fort Magsaysay in Laur, Nueva Ecija.
Under the plan, US troops will train eight regular infantry battalions in Mindanao and provide night-flying instructions to helicopter pilots operating out of the Visayas.
But unlike the training in Mindanao, which involved US military advisers going out on jungle patrols with their Filipino counterparts, the next phase will consist largely of classroom instruction and basic skill courses. – With Jose Katigbak, Washington bureau chief