By Zarak Khan | 2025-11-05

The recently concluded Seoul International Aerospace & Defense Exhibition (ADEX) has rapidly consolidated its status as a key strategic showcase for South Korea's expanding defense industry.

The event underscores Seoul's emergence as a pivotal supplier of advanced military systems to Indo-Pacific partners.

Those partners have become wary of China's increasingly assertive posture in major international waterways such as the South China Sea.

China claims more than 80% of that sea as its territory, though an international court rejected its case in 2016.

Held October 17–24 near Seoul, this year's ADEX enabled South Korea to display its growing technological sophistication while expanding security cooperation with regional partners including the Philippines, Japan and Indonesia.

These states, confronted with heightened geopolitical volatility, are accelerating defense modernization initiatives and exploring closer industrial and operational alignment with Seoul.

Philippines bolsters deterrence with Seoul

The Philippines, engaged in sustained maritime disputes with China, has become a leading customer for South Korea's air and naval technologies.

Manila is already a major operator of the FA-50 light combat aircraft and views South Korea as an indispensable partner in its military modernization.

Now it is considering buying South Korean fighter jets and submarines.

Korea Aerospace Industries (KAI), a South Korean firm, showcased its KF-21 Boramae 4.5-generation fighter jet at ADEX 2025. It is expected to rival China's J10 and FC31 fighters in the Asian market.

KAI confirmed it is in talks with the Philippines for potential acquisitions of the KF-21 Boramae.

Having a combat radius greater than 1,500 nautical miles and a service ceiling of 50,000 feet (15,240 meters), the KF-21 Boramae is designed for extended patrols and regional strike missions in critical zones like the East China Sea.

The KF-21 Boramae is "expected to rival China's J10 and FC31 fighters in markets such as Asia, Africa and the Middle East, and is set to enter service by the end of next year," the South China Morning Post reported October 27.

Philippine President Ferdinand R. Marcos Jr.'s four-day visit to South Korea, coinciding with the Asia-Pacific Economic Cooperation (APEC) summit in Gyeongju on November 2, further reinforced defense and economic ties.

On the sidelines of APEC, Marcos discussed possible contracts with major South Korean conglomerates, including Hanwha Ocean, the Philippine News Agency (PNA) reported.

Hanwha Ocean offered multiple options for building up the Philippine navy's submarine program, including "technology transfer, simulator training, and the construction of a submarine base and maintenance center in the Philippines," PNA reported.

It also wants to sell subs to Manila.

"Hanwha Ocean is actively proposing its KSS-III PN and Ocean 1400 submarines to the Philippine Navy," the Philippine Daily Inquirer reported in June.

Commitments from Japan, Indonesia

Japan, which has had rocky relations with South Korea, signaled renewed engagement by participating in ADEX for the first time in a decade.

Gen. Morita Takehiro, chief of staff of the Japan Air Self-Defense Force (JASDF), visited Korea and conferred with his South Korean counterpart, Gen. Son Sug-rag, marking the first such discussion since ADEX 2015.

The two officers confirmed the importance of both Japanese–South Korean security cooperation and trilateral ties with the United States and exchanged views on future exchanges and cooperation between their forces across various fields.

The JASDF will continue to "contribute to regional peace and stability, as well as the realization of a Free and Open Indo-Pacific, through cooperation with the Republic of Korea Air Force and other partners," said a statement from Japan's Defense Ministry.

Meanwhile, Indonesia, a partner in the KF-21 development program, signed a restructured agreement in June to continue its participation, setting its financial contribution at $439 million, according to South Korea's Defense Acquisition Program Administration.

An impressive exhibition

ADEX 2025, featuring 600 companies from 35 countries, positioned South Korea not merely as a rising defense exporter but as a technological anchor for states seeking to ward off China's insatiable maritime claims.

South Korea will "not only provide the world's best weapon systems but also share its industrial expertise and technological know-how with partner nations, becoming a reliable ally built on trust and cooperation," President Lee Jae Myung said October 20 at ADEX's opening ceremony.

The country will devote a "larger-than-expected budget" to defense and aerospace research until 2030 as it seeks to build the world's fourth-largest defense industry, he said.

South Korea ranked 10th among countries in arms sales as of 2023, according to the Stockholm International Peace Research Institute.

South Korea's growing defense independence and alignment with US partners have already drawn retaliation from Beijing.

China previously unveiled sanctions on Hanwha Ocean's US-linked affiliates, a move that could disrupt supplies of Chinese equipment and materials needed for shipbuilding cooperation between Seoul and Washington.