The Philippine Coast Guard (PCG) intensified its patrol operations in Batanes after it monitored three China Coast Guard (CCG) ships that appeared to be “bracketing” the island province from Taiwan on Friday, Aug. 8.

The PCG’s light utility Islander aircraft departed Manila at 6 a.m. and flew over the first CCG vessel with bow number “4304” approximately 75 nautical miles west off the coast of Sabtang Island.

The PCG aircraft issued a radio challenge to the Chinese ship, emphasizing that it lacks legal authority to operate within the Philippines' exclusive economic zone (EEZ).

“Unfortunately, the CCG vessel did not respond,” PCG spokesperson for West Philippine Sea (WPS), Commodore Jay Tarriela said.

The PCG aircraft failed to reach the two other Chinese vessels with bow numbers "3301" and "3304" a few miles away from the first ship due to adverse weather conditions.

Maritime security analyst Ray Powell said the three Chinese ships appeared to have been “bracketing” the coast of Batanes, the northernmost province of the country which faces Taiwan.

He described this as “a new level of aggression” on the part of the CCG.

“This is the first time I've observed this behavior from the China Coast Guard. While the CCG has been much more active in the West Philippine Sea, this marks the first [time] I've seen it extend its intrusive patrols east of the Philippines,” said Powell, a retired United States Air Force colonel and founder of SeaLight, a maritime transparency initiative at Stanford University's Gordian Knot Center for National Security Innovation.

Nonetheless, the PCG said it remains resolute and prepared to deploy additional resources should CCG vessels continue their presence or approach closer to the coastline of Batanes.

“The PCG is committed to protecting Philippine waters and will take necessary measures against any violations of the nation's maritime jurisdiction,” Tarriela stressed.

Top military and security officials previously bared efforts to fortify defenses in the northernmost part of the country in anticipation of China’s planned takeover of Taiwan.

Beijing has long considered Taiwan a breakaway province and has not ruled out the use of force to achieve what it calls “reunification.”

Over the past few years, China has ramped up military drills around the island, including large-scale air and naval exercises that simulate blockades and amphibious assaults.

Meanwhile, a suspected underwater drone has been discovered off the coast of Pangasinan, prompting coast guard officials to raise an alert.

The sea drone was found by local fishermen while they were engaged in a fishing expedition 149 nautical miles northwest off Bolinao town last Aug. 6.

According to the PCG, the fishermen initially spotted an orange object floating a few meters from where they were fishing so they went on to retrieve it.

Upon initial sighting, the fishermen said the object resembled features of an underwater drone. It measures 160 centimeters long, 20 inches wide, and weighs around 100 kilos.

The fishermen reported the incident to the Coast Guard Sub-Station Infanta, Pangasinan and turned over the drone to authorities.

The drone was subjected to further investigation and analysis.