The disputed South China Sea will soon see increased U.S. military activity from five Philippine bases, following the signing of a deal between Manila and Washington that will allow the Pentagon to deploy conventional forces to the Philippines for the first time in decades.

The deal — called an Enhanced Defense Cooperation Agreement — was reached Friday between State Department officials and the government of the Philippines, and will allow the Pentagon to use parts of five military installations: Antonio Bautista Air Base, Basa Air Base, Fort Magsaysay, Lumbia Air Base, and Mactan-Benito Ebuen Air Base. It comes at a time when the United States and its allies in the region have expressed concern about China increasingly deploying military assets to man-made islands in the South China Sea.

China has laid claim to a number of islands in the South China Sea, building airbases on tiny spits of land while installing powerful radar and missile launchers. Here's why. (Jason Aldag,Julie Vitkovskaya/The Washington Post / Satellite photos courtesy of CSIS)

State Department spokesman John Kirby, a retired two-star Navy admiral, said that the United States has “made absolutely no bones about the fact that we take the rebalance to the Asia Pacific region very seriously.” But he added that there is “nothing offensive or provocative” about any of the Pentagon’s deployment of troops to the region.

“It’s not about selling it to the Chinese or to anybody,” Kirby said, under questioning during a media briefing. “It’s about meeting our security commitments in a serious alliance with the Philippines. That’s what this is about.”

The map above shows where the bases are. Antonio Bautista Air Base, on the island of Palawan, is a few dozen miles east of the disputed Spratly Islands, where China’s military buildup is underway. Basa Air Base is also near the South China Sea, and is in a rural area outside Manila. Bautista Air Base is the closest installation the Philippines has to the Spratlys, according to Philippine air force. Other bases were considered, according to Philippine media reports, but ultimately not included in the agreement.

China raised questions about the plan Monday, saying that cooperation between the United States and the Philippines should not harm the sovereignty or security interests of any other country.

“The U.S. has talked about militarization in the South China Sea. But can it explain whether its own increased military deployment in the region is equivalent to militarization?” said Chinese Foreign Ministry spokesperson Hua Chunying said at a media briefing, according to Xinhua, a state-run news agency.

The United States had a conventional military presence in the Philippines for nearly a century until 1991, when the country ordered the U.S. military to leave its naval base in Subic Bay after the countries could not reach an agreement on the extension of a lease. A U.S. Special Operations task force was based in the Philippines for 13 years after the Sept. 11, 2001 attacks, but was phased out last year in favor of keeping a small amount of U.S. troops nearby to assist Philippine forces in their fight against Islamist militants.