FORT MAGSAYSAY, Philippines >> The squad from the U.S. Army’s 196th Infantry Brigade was moving quietly through the hills of Luzon Island when the staccato bursts of machine gun fire sent them into action.

About a dozen soldiers fired into the surrounding mountains, while a small contingent broke away to make a direct assault on the hidden gunmen. After a brief, intense gun battle, the squad cleared the area.

The firefight was part of joint military exercises in which the message, at least in part, appeared to be clear despite proclamations to the contrary. The exercises included mock beach invasions along coastlines facing China, whose military buildup and territorial claims in the South China Sea have alarmed some of its neighbors and jumpstarted the U.S. military “pivot” to the region.

That U.S. policy, which will include sending more troops and ships to the region, appears to have picked up speed in recent weeks.

On Thursday, Japan and the U.S. announced what was effectively a compromise on Okinawa that calls for thousands of Marines to leave for Guam in an attempt to allow others to remain on the strategic island despite local objections. And on Monday, Secretary of State Hillary Rodham Clinton and Secretary of Defense Leon E. Panetta will meet their Philippine counterparts in Washington, the highest level meeting after months of talks to expand the U.S. military presence in the Philippines.

Ramping up the number of troops in the Philippines — even if they are rotating in and out from temporary bases as predicted — would still be something of a reversal for the nation after Philippine lawmakers forced the closing of U.S. bases, including the shuttering in 1992 of the Subic Bay Naval Station. The base, which had been a cornerstone of the U.S. military presence in Asia for nearly a century, was a casualty of some Filipinos’ sense that the facility served as a painful reminder of decades of U.S rule.

Such feelings still exist among some Filipinos; hundreds of people protested in Manila against the recent joint exercises and as talks in Washington approached, activists sent out a media alert of planned protests Monday near the U.S. Embassy. (The alert included a fake government seal, labeling the foreign ministry a “U.S. satellite office.”)

But fear of a rising China has confirmed for many Filipinos — including President Benigno S. Aquino III — that the country needs an increased American military presence. A continuing standoff with China over Scarborough Shoal, in which patrol boats from both nations are positioned near the rock outcroppings, has added to concerns about the Philippines’ vulnerability.

A Congressional Research Service report published this month called the relationship with the Philippines “a key link in the evolving U.S. foreign policy ‘pivot’ or ‘rebalancing’ toward Asia, particularly Southeast Asia.”

Despite the closing of Subic Bay, the U.S. military presence in the Philippines has grown in recent years. Beside the joint military exercises that occur annually, the U.S. keeps about 600 troops at a time in the Philippines, many of them trainers assisting in counterterrorism efforts in the south. The mission started the year after the Sept. 11, 2001, terrorism attacks in the U.S. as the Bush administration sought to smother terrorist groups worldwide, especially those linked to al-Qaida.

The renewed interest in building up forces in the Philippines has been evident for months. In November, Clinton traveled to Manila and proclaimed, on the deck of a U.S. warship in Manila Bay, continued military support for the Philippines. She also irritated the Chinese by referring to an area of the South China Sea as the West Philippine Sea, a name used by the Philippines but not other nations. (The Scarborough Shoal lies within those waters.)

Several members of Congress have also visited the country in recent months to discuss military cooperation, including Sen. John McCain, R-Ariz., and Sen. Joseph Lieberman, I-Conn., both senior members of the Senate Armed Services Committee.

The political sensitivity over U.S. troops in a former colony goes a long way toward explaining how carefully both Philippine and U.S. officials have presented negotiations over possibly increasing military ties.

Raul Hernandez, a spokesman for the Philippine Department of Foreign Affairs, was quick to stress in a recent interview that permanent U.S. military bases were not being considered.

“We are fine-tuning and readjusting our engagement,” he said. “We are talking about more frequent visits and more engagement with the United States, not about military bases. What is very sure, whatever arrangements are made, they will conform to our laws and our Constitution.”

That type of relationship, in fact, is emblematic of what American officials say the new “pivot” will mainly look like. Reflecting the stated need to shrink the military budget, and the difficulties in winning approval for permanent bases abroad, the new security strategy called for more rotational deployments.

In those cases, U.S. troops would be operating on a temporary basis in other countries and live in less permanent facilities.

For those Filipinos sensitive to increased forces, there may not be much of a distinction between permanent and temporary.

A preview of what such arrangements might look like can be found on the southern island of Mindanao. At a Philippine military base in Zamboanga, a city on Mindanao, several hundred members of the U.S. military have been serving on a rotating basis — for nearly a decade.

The Joint Special Operations Task Force Philippines has a public affairs officer, a dedicated website and a mess hall outfitted by the same agency that stocks American military base dining facilities around the world.

The Zamboanga facility also has videoconferencing services for soldiers to communicate with their families.

In 2009, a Philippine Navy lieutenant, Nancy Gadian, told the Philippine Senate that when she was stationed in Mindanao she had worked with the Americans serving there. She testified that the U.S. had built “permanent structures” at sites around the southern Philippines that are off-limits to the Philippine military. The U.S. consistently says it has no permanent bases in the country.

Though the Zamboanga facility has many hallmarks of an overseas military base, its website states: “U.S. forces are temporarily deployed to the Philippines in a strictly noncombat role to advise and assist the AFP” — the Armed Forces of the Philippines — to “share information, and to conduct joint civil-military operations.”

While the details of a potential increase in the U.S. military presence have not been announced, there may be a clue in a recently announced business deal to what may be about to happen. On April 18, a subsidiary of the U.S. defense contractor Huntington Ingalls Industries announced a deal to work with Hanjin Heavy Industries, which maintains a large shipbuilding and repair facility at the former base at Subic Bay. That opens the door to large-scale servicing of U.S. military ships in Subic Bay for the first time in almost 20 years.

In a news release announcing the deal, Huntington Ingalls said the companies “will work together in providing maintenance, repair and logistics services to the U.S. Navy and other customers in the Western Pacific region.”

© 2012 The New York Times Company