Keen Sword 27: U.S. and Japan Open Largest-Ever Island Defense Drills

Japanese and U.S. forces begin Keen Sword 27 on Monday, Oct. 19, opening an 11-day exercise that rehearses the defense of Japan’s southwestern islands and runs through Oct. 29. About 45,000 Self-Defense Force personnel and roughly 12,000 U.S. service members are taking part, making it the largest edition of the drill to date, The Japan Times reported. The exercise will put American anti-ship missile launchers on Yonaguni, the Japanese island closest to Taiwan, for the first time.

Keen Sword 27 at a glance

• Dates: Oct. 19 to Oct. 29, 2026, according to a Sept. 29 news release from Japan’s Joint Staff Office.
• Japanese forces: 45,000 personnel, 6,100 vehicles, about 40 vessels and 260 aircraft, the Joint Staff said, as reported by Stars and Stripes.
• U.S. forces: U.S. Forces Japan, Indo-Pacific Command and the Army, Navy, Air Force and Marine Corps Pacific commands. The Japan Times put U.S. participation at about 12,000 troops.
• Commanders: Adm. Tateki Tawara, head of Japan’s Joint Operations Command, and Adm. Steve Koehler, commander of the U.S. Pacific Fleet, USNI News reported.
• Other countries: Japanese planning documents list Australia, Canada, France, Germany, the Netherlands, New Zealand and the Philippines as observers or participants in some drills.
• Live fire: None of the new missile systems will be fired, a Joint Staff spokesman told Stars and Stripes.

Keen Sword is the allies’ largest field training exercise. It has been held since 1985 and alternates with a tabletop exercise called Keen Edge. The program for this year covers air and missile defense, surface warfare, amphibious landings, airborne operations and the reinforcement of remote islands by sea and air.

U.S. missiles head to Yonaguni and the Sakishima Islands

About 60 troops from the U.S. Marine Corps’ 12th Marine Littoral Regiment and the U.S. Army will deploy to Yonaguni with the Navy-Marine Expeditionary Ship Interdiction System, or NMESIS, and the Marine Air Defense Integrated System, known as MADIS, according to a Japanese Defense Ministry planning document cited by Stars and Stripes. A Yonaguni town spokesman told the paper it would be the first time either system has been sent to the island, which sits about 110 kilometers (roughly 70 miles) east of Taiwan.

NMESIS mounts Naval Strike Missiles on light tactical vehicles to hit ships at sea. MADIS pairs Stinger missiles with a 30 mm cannon to counter drones and low-flying aircraft. Both are central to the Marine Corps’ plan to operate small units from islands inside the range of enemy weapons.

The deployments stretch along the island chain. On Ishigaki, U.S. Army and Marine units will bring NMESIS, MADIS and the High Mobility Artillery Rocket System, or HIMARS, alongside Japanese Type 12 and Type 88 anti-ship launchers, USNI News reported. About 120 Marines are set for Miyako Island, and around 400 Marines will join 1,500 Japanese ground troops on Tanegashima, south of Kyushu. Japan’s Amphibious Rapid Deployment Brigade will practice landings at Kin Blue Beach and Camp Hansen on Okinawa from Oct. 20 to 23 with about 400 personnel and 12 AAV-7 amphibious vehicles.

Japan’s Air Self-Defense Force will also rehearse losing Naha Air Base, dispersing four F-15 fighters each to Tokunoshima Airport, Amami Airport and Kadena Air Base. The planning documents did not mention the U.S. Army Typhon launcher stored at Kadena, which drew protests from China and Russia after drills on Kyushu last month.

Japan’s Type 25 missile leaves its base for the first time

Launchers for Japan’s new Type 25 surface-to-ship missile left Camp Kengun in Kumamoto on Sunday morning, Oct. 18, bound for the Ohnohara training area on the border of Nagasaki and Saga prefectures, Kyodo News reported, as cited by Taiwan Defence. The Type 25 is an upgraded version of the Type 12 with a range of roughly 1,000 kilometers (about 620 miles). It has been stationed at Kengun since March 31, and the Joint Staff spokesman told Stars and Stripes that this is the first time it has deployed elsewhere. It will be used in anti-ship training but not fired.

Tokyo bought the missile as part of the counterstrike capability adopted in its 2022 national security strategy, which allows Japan to strike enemy launch sites in response to an attack. From Kyushu, a 1,000-kilometer range would cover the Korean Peninsula, the waters around Taiwan and parts of China’s coast.

A carrier arrives, and a strained backdrop on Okinawa

The carrier USS Theodore Roosevelt, the cruiser USS Chosin and the destroyer USS Decatur arrived at Yokosuka on Oct. 16 ahead of the drills, USNI News reported, making the Roosevelt the first carrier not based in Japan to enter the port in four years. The Yokosuka-based George Washington strike group has been operating in the Middle East since July. The drills also follow a Chinese military combat readiness patrol around Taiwan on Oct. 14.

Keen Sword also opens two weeks after Okinawa police arrested Lance Cpl. Devin Jacob Ballard, 20, a Marine stationed at Marine Corps Air Station Futenma, on suspicion of the robbery and murder of Anna Yagi, 39, at a Naha hotel on Oct. 3. Police said he has denied the allegations. U.S. forces on Okinawa held a 48-hour training pause with an alcohol ban and then began a 30-day midnight-to-5 a.m. curfew on Oct. 9, The Japan Times reported. The curfew overlaps the entire exercise. Secretary of State Marco Rubio pledged U.S. cooperation with the Japanese investigation, Al Jazeera reported.

Reactions

“Through this exercise, the JSDF and U.S. Forces will maintain and strengthen the posture and capabilities necessary to actively contribute to regional peace and stability,” Japan’s Joint Staff Office said in its release. U.S. Forces Japan declined to comment on the deployments when asked by Stars and Stripes.

Lt. Gen. Benjamin Watson, commander of the III Marine Expeditionary Force, wrote in announcing the curfew that “serving on Okinawa comes with responsibility” and that commanders would “think hard about discipline, standards and our alliance responsibilities.”

Some Japanese communities have objected. A residents’ group asked the Defense Ministry and Tsuiki Air Base in Fukuoka on Oct. 13 to cancel the exercise, and residents raised concerns at a public meeting in Miyakojima on Oct. 17, according to the Asahi Shimbun and Miyako Shinpo as cited by China’s state-run Global Times. In Oita, opposition groups and prefectural assembly members petitioned the governor on Oct. 15, citing the Okinawa case. Lü Chao, a professor at the Liaoning Academy of Social Sciences, told the Global Times that the Type 25 deployment “amounts to a clear provocation.”

For more coverage of military tensions across Asia and the Middle East, see The Boston Report’s Geopolitics hub.

Featured photo: U.S. Marines and members of Japan’s Amphibious Rapid Deployment Brigade walk to an MV-22 Osprey during Keen Sword 25 at Marine Corps Air Station Futenma, Okinawa, on Oct. 28, 2024. U.S. Marine Corps photo by Staff Sgt. Manuel Serrano, public domain, via Wikimedia Commons (cropped).

Sources

• The Japan Times: Joint Japan-U.S. military drill set to break new ground
• USNI News: U.S., Japanese Forces to Rehearse Defense of Japan’s Southwest Islands
• Stars and Stripes: Marines to bring new missile systems closer to Taiwan during Keen Sword exercise
• Taiwan Defence: Japan’s Type 25 long-range missiles leave their Kumamoto base for a first big exercise
• USNI News: Carrier USS Theodore Roosevelt Arrives in Japan
• The Japan Times: U.S. military in Okinawa pauses operations and enforces curfew in wake of murder
• NBC News: U.S. Marine arrested on suspicion of killing Japanese woman in Okinawa
• Al Jazeera: Rubio pledges US cooperation in Marine-linked murder case
• Global Times: US-Japan ‘Keen Sword 27’ drills to begin amid protests in Japan