Japan and the Philippines Increase Their Focus on Island Defense

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Japan and the Philippines Increase Their Focus on Island Defense

Growing Chinese assertiveness in the East and South China seas has forced the two U.S. allies to reorient their defense strategies.

Japan and the Philippines Increase Their Focus on Island Defense

A U.S. Army UH-60 Blackhawk helicopter flies over Batanes islands towards Itbayat, the Philippines’ northernmost town, during a joint military exercise on Monday, May 6, 2024.

Credit: AP Photo/Aaron Favila

The Philippines and Japan have increased their focus on defending their small islands near Taiwan, investing in new military capabilities and expanding training with the United States in a trend that reflects both countries’ growing concern about tensions across the Taiwan Strait and about the impact of a possible conflict there.

China considers Taiwan a breakaway province and has vowed to unify with it, by force if necessary. Like the U.S., neither Japan nor the Philippines has formal relations with Taiwan and they have not committed to defend it, but both have islands that are just a few dozen miles away and are increasingly worried about securing their territory and citizens if China moves to isolate and absorb Taiwan.

“We can see that just by our geographical location, should there in fact be conflict” around Taiwan, “it’s very hard to imagine a scenario where the Philippines will not somehow get involved,” Philippine President Ferdinand Marcos Jr. told Nikkei Asia in February 2023.

“We feel that we’re very much on the front line,” added Marcos, whose home province of Ilocos Norte, in northwestern Luzon, faces Taiwan across the Luzon Strait.

“Key Maritime Terrain”

An emphasis on island and coastal defense was visible in the most recent Balikatan exercise in the Philippines, which concluded on May 10. During the exercise’s final week, U.S. and Philippine troops conducted a counter-landing exercise in Ilocos Norte, using missiles, artillery, and machine guns against a simulated invasion force at a beach picked in part for its “proximity to strategic waterways.” Days later, U.S., Philippine, and Australian forces worked together to sink a target ship in the same area during an exercise meant to strengthen their “proficiency in naval interdiction and deterrence operations.”

To the east, U.S. and Philippine troops set up sustainment hubs to support operations around northern Luzon and the islands of Batanes, the Philippines’ northernmost province. U.S. and Filipino soldiers also used a northeastern Luzon airfield to insert and conduct simulated strikes with HIMARS rocket artillery to improve their ability to collaborate “in complex littoral and coastal defense operations” before driving the HIMARS launcher north to prove it could reach a port using the island’s roads.

North of Luzon, U.S., Philippine, and Australian troops conducted air-assault drills, inserting by helicopter onto Batan and other islands overlooking the Bashi Channel between the Philippines and Taiwan. U.S. and Philippine Marines also trained to secure the Philippines’ three northernmost islands, which are roughly 160 kilometers south of Taiwan, and to monitor activity in the surrounding waters.

During that training, the Marines worked together “to secure key maritime terrain in a scenario designed to preserve Philippine territorial integrity,” Lt. Col. Mark Lenzi, commander of the 3rd Littoral Combat Team, part of the 3rd Marine Littoral Regiment (MLR), said in a press release.

The drills in the northern Philippines continue Balikatan’s recent shift to that part of the country. During Balikatan in 2022, members of the 3rd MLR, which had been activated only a few weeks prior, trained along Luzon’s northern coast for the first time, moving away from their usual exercise sites in the central Philippines. Balikatan 2023 returned to the same area, with U.S. and Philippine Marines and soldiers conducting air assault drills on “key maritime terrain” on islands in Luzon and Batanes.

The move north also comes amid a broader reorientation by the Philippine military to defense against external threats after decades of focusing on domestic insurgencies. Lenzi said this year’s drills were meant to support the Philippines’ Archipelagic Coastal Defense Concept, which emphasizes the defense of Philippine territory and sovereign rights, including in the exclusive economic zone extending 200 nautical miles from its coast.

Manila is making other moves to improve its posture in the north. Defense Secretary Gilberto Teodoro Jr. in February called for a greater military presence in Batanes, describing it the “spearhead” in the northern Philippines. Since then, the military has deployed more naval reservists, installed new “high-tech” radios at bases, and begun building new infrastructure, including on Mavulis, its northernmost island. There are also plans to build a new port in Batanes, which the governor has said could aid the evacuation of Filipinos from Taiwan.

The United States is assisting the effort, building a warehouse in Batanes to support Philippine construction work and “ensure that residents become comfortable with their recurring presence,” according to Bloomberg. Washington is also making upgrades at several Philippine bases, including in northern Luzon, where it has been allowed access under the 2014 Enhanced Defense Cooperation Agreement (EDCA) – access that Marcos has said could be “useful” if China attacks Taiwan.

Despite the northward shift, Manila still has other priorities. It faces aggressive pressure from China in the South China Sea – many Balikatan drills this year took place in or facing that waterway – and EDCA cooperation “remains mainly focused” on that and on improving disaster-response capabilities and U.S.-Philippine interoperability, said Greg Poling, director of the Southeast Asia Program at the Center for Strategic and International Studies.

But tensions over Taiwan have made an impression in Manila. “Philippine officials realize that with or without the American alliance, their interests will be directly threatened by any violence over Taiwan,” Poling said in an email in December. “So there are good reasons for the Philippines to want to increase its presence and capabilities in northern Luzon, which is helped by U.S. construction at the EDCA sites.”

“An Urgent Task”

Japan has also increased its focus defending its Nansei (Southwest) Islands, which stretch some 1,100 kilometers from Kyushu, the southernmost of its four main islands, to Yonaguni, a small island about 100 kilometers from Taiwan, in response to Chinese military activity that has increased in scope, scale, and frequency since the early 2010s.

That activity and the proximity of those islands to Taiwan has led Japanese leaders to link their country’s security to Taiwan’s, a view reflected in recent official statements and documents. Their concern was heightened by China’s major exercise around Taiwan in August 2022, during which Chinese missiles landed in Japan’s exclusive economic zone for the first time, drawing a protest from Tokyo.

China’s navy and air force “have expanded and intensified their activities in the ocean and airspace surrounding Japan” and “this pressure has been particularly high in the southwestern islands of Japan in recent years,” Lt. Gen. Yamane Toshikazu, vice chief of staff for Japan’s Ground Self-Defense Force (JGSDF), said at a conference in Washington, D.C. in October 2022.

In response, Yamane said, the JGSDF has been shifting its focus from east to its west, establishing new outposts on southwestern islands, and “enhancing maneuver and deployment capabilities to deploy units in the southwestern region.”

That effort has seen new garrisons and new forces, including electronic-warfare and anti-ship and air-defense missile units, deployed over the past decade, including to Yonaguni and Ishigaki at the western end of the chain and Miyako, Okinawa, and Amami Oshima, which overlook major straits in the center of it. Japan is also hardening facilities in the area and building new ammunition depots that will also support the counterstrike missiles being deployed in the coming years.

Japan faces “the most severe and complex security environment” since World War II, and it “is in the process of fundamentally strengthening its defense capabilities, and in particular strengthening the defense system in the southwest region is an urgent task,” Defense Minister Kihara Minoru said in late March. He was speaking at the activation ceremony for a new regiment of the Amphibious Rapid Deployment Brigade (ARDB), which was set up in 2018 to counter threats to Japan’s islands. (The ARDB is the first Marine unit Japan has had since World War II.)

The focus on island defense has also influenced recent exercises with the United States. During Orient Shield, an annual Japan-U.S. army exercise, in 2021, air-defense units trained on Amami Oshima in “an Anti-Access Area Denial scenario” for the first time. During the 2022 edition of the exercise, troops trained to defend the island against an attack from the sea. (U.S. HIMARS launchers also deployed to the Nansei Islands for the first time during Orient Shield 2022 and remained there afterward to support future training.)

In March 2023, Iron Fist, an annual Japan-U.S. exercise that began in the mid-2000s, was held in Japan for the first time. It saw U.S. and Japanese paratroopers and Marines conduct a simultaneous airdrop and amphibious assault on an island near Amami Oshima to practice “taking an island by air, land, and sea.” During another exercise later that year, U.S. and Japanese troops trained at a newly opened base on Ishigaki, less than 300 kilometers from Taiwan’s east coast, to practice “deploying and dispersing throughout the first island chain.”

Iron Fist returned to the Nansei Islands this year and again featured training to recapture remote islands, using Okinoerabu, near Okinawa, for the first time to expose troops to unfamiliar territory. Speaking at the end of the exercise, ARDB commander Maj. Gen. Kitajima Hajime said, “We will show to the world that any attempt to invade Japan will end in failure in the face of the Japan-U.S. alliance.”


The focus on the Japanese and Philippine islands nearest Taiwan reflects their importance not only to operations around Taiwan but for any operations along the first island chain, which runs from Japan through Taiwan and the Philippines to Indonesia. Since they overlook major straits in that chain, those islands are assets for whoever occupies them and obstacles to anyone trying to get by them.

“They’re geographically proximate to Taiwan and those key waterways in which and above which [Chinese] air and naval forces would seek to transit” to reach the Western Pacific, said Collin Koh, a senior fellow at the S. Rajaratnam School of International Studies in Singapore.

Because of their location, the Philippine and Japanese islands closest to Taiwan “would hold the key to not only constricting or containing” China’s access into the Western Pacific “but also to facilitate U.S. military movement west of the First Island Chain,” Koh said in an email in December.

Those islands “are gatekeepers” that could help deny China access to key waterways and airspace and “help facilitate U.S. and allied access to the same waterways to conduct combat operations” near China, Koh added.

China’s military activity in the area reflects its focus on being able make such a breakout. Its warships have for years conducted major drills to simulate forcing their way through Japan’s Nansei Islands. Its ships and planes are now a near-constant presence around those islands and around the Bashi Channel, training and gathering information on the environment and on rival forces.

While Japan and the Philippines are both boosting their military capabilities, it’s not certain whether or how either would join in defending Taiwan if it were attacked by China. Elected officials and other leaders in each country are worried about getting caught in a major war and have expressed concern about the military buildup around them.

Absent a direct attack on them by China, Tokyo or Manila may offer only limited support to the United States in such a conflict. Even if those countries try to limit their involvement, however, Chinese military planners may decide that they need to attack U.S. forces on their soil “to improve their security and reduce their vulnerability to U.S. weapons” while operating around Taiwan, according to Timothy Heath, a senior international defense researcher at the Rand Corporation.

“If the U.S. is in the fight, then the Chinese military planners have to be willing to strike targets in Japan, including the Ryukyu Islands, where the U.S. has a lot of combat power, mainly air power and some ships, and the Philippines, where the U.S. may have air defense or some air base access,” Heath said in December. “So the Chinese probably would be prepared to extend the war with Japan and the Philippines as well as the U.S. if they go down that route.”