China builds ‘unprecedented’ maritime presence east of Taiwan

China has deployed survey and law enforcement ships to conduct "unprecedented operations" in the Philippine Sea east of Taiwan, according to a new report from the Asia Maritime Transparency Initiative published on August 19, marking what analysts describe as an escalation of Beijing's efforts to assert control over contested waters.

Beijing Responds to Japan-Philippines Cooperation

The AMTI report details how China responded swiftly after Japan and the Philippines announced maritime boundary delimitation talks in late May 2026. Within days, China's Ministry of Transport deployed large patrol vessels, including the 10,000-ton Hai Xun 09, to conduct "maritime traffic law enforcement and hydrographic survey operations" in the Philippine Sea.amti.csis+1

During these operations, Chinese law enforcement hailed 198 commercial vessels transiting the area and demanded information about their crew and destinations — actions AMTI describes as unlawful even if conducted within China's own exclusive economic zone. Between June and August, China Coast Guard vessels maintained a near-continuous presence in the area, where virtually no Chinese law enforcement had been observed in the preceding five months.thevibes+1

"The scale and character of China's response suggest that these operations are not just about sending a signal to Tokyo and Manila," AMTI stated, warning that Beijing may be seeking to "change the status quo by establishing a semi-permanent presence and exercising some form of jurisdiction east of Taiwan".amti.csis

Indonesia-China Exercise Draws Protests

Adding to tensions, China and Indonesia conducted a joint naval passage exercise east of Taiwan in mid-August — the first time China and a foreign navy have operated together in those waters. Taiwan's Mainland Affairs Council "strongly condemned" the exercise as a "military provocation" that infringes on Taiwan's sovereignty.focustaiwan+1

According to ABC News, a senior Taiwanese intelligence official said the Indonesian frigate KRI Gusti Ngurah Rai was detected approximately 80 nautical miles off Taiwan's east coast. Indonesia's Ministry of Defence described it as a routine passing exercise conducted while the vessel transited home from exercises in Russia, though analysts at the University of Melbourne warned that "Beijing is using Jakarta to further its own agenda to squeeze Taiwan".indonesiaatmelbourne.unimelb+1

Broader Pattern of Pressure

The developments occur against a backdrop of intensifying Chinese maritime activity around Taiwan. A total of 263 Chinese ships were detected in waters around Taiwan in June alone, up from 171 in June 2025, according to Taiwanese coast guard data reported by The Defense Post. China Coast Guard ships have continuously patrolled east of Taiwan since June 1, and the PLA Southern Theater Command conducted joint naval and air training near Scarborough Shoal on August 1.aei+2

AMTI warned that the operations "could function as a rehearsal for a quarantine effort to test regional reactions and normalize a low level of coercion," and noted that Australia, France, Germany, Taiwan, the United Kingdom, and the United States have all condemned China's expanded operations.amti.csis