Flashpoints | Security | East Asia

Taiwan Wants to Know Why Indonesia Joined China in a Naval Exercise East of Taiwan

The exercise highlighted increasing tensions in the waters east of Taiwan, which are also close to Japan and the Philippines.

This undated photo, released by China’s military, shows the Honghe, the frigate that took part in the passex with Indonesia on Aug. 12, 2026.

In a rare moment of diplomatic friction, Taiwan has called on the Indonesian government to clarify joint naval exercises with China that took place in waters east of Taiwan. 

The exercise took place on the morning of August 12, between 6:30 a.m. and 9:30 a.m. As part of the naval exercise, the Indonesian Navy frigate KRI I Gusti Ngurah Rai and the Chinese People’s Liberation Army Navy’s Honghe, a guided-missile frigate under the Eastern Theater Command, practiced maritime maneuvers. The drill included practicing formation, maritime communications, as well as replenishment-at-sea, and concluded with a divergence ceremony.

For its part, the Indonesian government has denied that the exercise was threatening in any way.

“The passing exercises are not war-fighting in nature, but rather a universal naval tradition conducted when passing through the waters of another country,” the Indonesian Navy said in a statement. It described passex activities in general – including, presumably, the one on August 12 – as “goodwill engagements that are commonly conducted by navies around the world as an expression of naval brotherhood and the maritime diplomacy associated with warships.” 

Similarly, the Chinese government claimed that the exercises were in the interests of “jointly safeguarding regional peace and stability.”

Certainly, the scale of the exercise is not to be overstated, as it only involved two vessels. At the same time, according to geointelligence firm ingeniSPACE in a report published by Domino Theory, the exercise took place in Taiwan’s exclusive economic zone (EEZ). The Indonesian vessel, which had its Automatic Identification System (AIS) on, first entered Taiwan’s EEZ before aligning with the Honghe, which did not have its AIS on – as is common for Chinese vessels operating in Taiwan’s EEZ. The Indonesian frigate later passed close to but did not enter Taiwan’s contiguous zone. 

Before its joint exercise with the Honghe, the I Gusti Ngurah Rai had participated in a bilateral exercise, the Orruda 2025, with the Russian navy in late July. After docking at Yokosuka Naval Base in Japan from August 1 to August 8, it later set out for the joint exercise with the PLAN. After that, the Indonesian vessel entered the Philippines’ EEZ and was expected to pass through Scarborough Shoal, a disputed reef claimed by both China and the Philippines. 

Some analysts have read the joint exercise as intended to hit out at increased maritime cooperation between the Philippines and Japan. The two countries held joint exercises with the United States at the end of July in the South China Sea. The drills took place not too long after a renewed round of confrontations between the Philippines and China around Scarborough Shoal, with Manila accusing China of firing water cannons at its vessels, while China hit out at the Philippines for what it claimed was an illegal blockade. 

The Philippines and Japan have increasingly set aside differences in the interests of maritime cooperation as of late. The two countries agreed in late May to delimit their overlapping EEZs and continental shelves in waters east of Taiwan. Such a move may have been aimed at strengthening Japan-Philippines cooperation in the event of a Taiwan contingency.

However, this area also partially overlaps with Taiwan’s EEZ, so Taiwan responded by asserting its own sovereign claims. While Taiwanese political leaders have praised the talks, Taiwan may not want to be left out of talks in which it could be a stakeholder. 

China also objected to the Japan-Philippines talks on the grounds of its claim to control Taiwan – and thus Taiwan’s EEZ. Beijing demanded that Japan and the Philippines “immediately cease all illegal acts that undermine China’s sovereign rights and........

© The Diplomat