Some Chinese government vessels have committed “provocative acts”, including illegally sending radio challenges against Philippine authorities patrolling the country’s waters, the Department of Foreign Affairs (DFA) reported on Wednesday night.

In a statement posted on its official Twitter account, the DFA said it protested the “unlawful issuance of over 200 radio challenges, sounding of sirens, and blowing of horns by Chinese government vessels” against Filipino authorities “conducting legitimate, customary, and routine patrols over and around the Philippines’ territory and maritime zones.”

“These provocative acts threaten the peace, good order, and security of the South China Sea and run contrary to China’s obligations under international law,” it said.

It is not clear when the said incidents occurred. As of this posting, the DFA has yet to provide further details.

The Philippines has issued a number of diplomatic protests this year alone over the illegal presence and activities of Chinese vessels within the country’s 200-nautical-mile exclusive economic zone.

Last September, Foreign Affairs Secretary Teodoro Locsin, Jr. instructed the agency to lodge a note verbale against Beijing’s “incessant and unlawful” restriction imposed on Filipino fishermen in the Scarborough Shoal, a feature located 124 nautical miles off the coast of Masinloc, Zambales.

He also ordered a set of protests on Chinese radio challenges “unlawfully issued against Philippine maritime patrols” and the continued presence of Chinese fishing vessels in the vicinity of Iroquois Reef.