By Focus | 2025-12-25

As co-host of the second ASEAN-US Maritime Exercise (AUMX) in 2025, Indonesia demonstrated its role in advancing regional defense and maritime security in the Indo-Pacific, stakeholders said.

The exercise, held December 9–13 in Batam, Riau Islands, brought together the US Navy and navies from ASEAN for a series of drills aimed at strengthening interoperability, trust and maritime cooperation. The only previous AUMX occurred in 2019.

"Batam is not only strategically important but also demonstrates Indonesia's strong maritime heritage, making it an ideal location for this maritime exercise," said Lt. Gen. Tri Budi Utomo, secretary-general of Indonesia's Ministry of Defense.

"Through this exercise, we reaffirm our commitment to maintaining maritime stability and ensuring the region remains peaceful and secure," he added, ANTARA News reported December 10.

Stronger together

AUMX 2025 included subject matter expert exchanges on the United Nations Convention on the Law of the Sea and medical evacuation (MEDEVAC) procedures, according to the US Navy.

The Indonesian and US navies conducted a tabletop exercise in which ASEAN member states executed a simulated MEDEVAC scenario, reinforcing operational coordination.

That led into the sea phase of the exercise, where participating ships conducted communication checks, tactical maneuvering and damage control, as well as screening, search and rescue, and MEDEVAC drills, the US Navy said.

"These at-sea serials are routine for each of us individually, but the ability to conduct them together is where our strengths lie," US Navy Capt. Matt Cox, deputy commodore of Destroyer Squadron 7 (DESRON 7), said in a statement published December 13.

"Strength through partnerships is how we are able to deter aggression effectively and ensure peace and prosperity in the region."

DESRON 7 is the US Navy's primary tactical and operational commander of littoral combat ships rotationally deployed to Southeast Asia from Singapore. It regularly conducts training exercises and military-to-military engagements in the region as commander of the Task Group Cooperation Afloat Readiness and Training (CARAT) exercises.

Building interoperability at sea

The two-day sea phase in the Singapore Strait concluded AUMX 2025.

Indonesia deployed the Bung Tomo-class corvette KRI John Lie along with a Bell helicopter, while the US Navy contributed the Independence-class littoral combat ship USS Cincinnati and a drone.

Brunei participated with the Darussalam-class offshore patrol vessel KDB Darulaman, Malaysia with the Kasturi-class corvette KD Lekir, Burma with the guided missile stealth frigate UMS Kyan-Sit-Thar, the Philippines with the guided missile frigate BRP Antonio Luna, Singapore with the Victory-class corvette RSS Vigour and Vietnam with VPN Ship-09.

Cambodia, Laos, Thailand and Timor-Leste joined AUMX 2025 as augmented staff.

"I'm extraordinarily proud of the successful execution of AUMX 2025," Cox said.

"Our seamless integration into an exercise of this scale demonstrates the interoperability we have with our ASEAN partners. We rely on them to help uphold security and stability in the Indo-Pacific region, and we value the opportunity to operate together."

Indonesia's role as co-host highlights its central position in advancing regional defense and security in line with the ASEAN Outlook on the Indo-Pacific, Utomo said, according to ANTARA News.

AUMX supports real-time multilateral information sharing and maritime incident response in accordance with international law, including principles of freedom of navigation, he added.

At the first AUMX, back in September 2019, pre-sail activities took place in Thailand, Singapore and Brunei. A sea phase in international waters in Southeast Asia, including the Gulf of Thailand and the South China Sea, followed.