Taiwan has accused China of “harassing” commercial vessels in waters east of the island, as both sides clashed over the legality of recent Chinese coast guard patrols.

According to Taiwan’s Coast Guard Administration, Chinese vessels since June 7 have broadcast messages to at least three merchant ships, demanding details on their point of origin and destination while asserting jurisdiction over the area. Taipei said its own ships told the merchant vessels to ignore the Chinese inquiries and insisted China has no right to intervene in those waters.

Beijing defended the operations. Chinese state media reported the patrols were launched June 6 as part of a “special maritime traffic law-enforcement” mission, in response to recent maritime boundary discussions between Japan and the Philippines. China’s Taiwan Affairs Office said the coast guard was conducting “law-enforcement patrols” in accordance with the law and called it a legitimate act to safeguard sovereignty and maritime rights.

The dispute has heightened tensions around Taiwan’s eastern waters. Taiwan Foreign Minister Lin Chia-lung described China’s actions as “expansion” under the guise of law enforcement and said Beijing was damaging the status quo. China maintains Taiwan is part of its territory and rejects Taipei’s sovereignty claims.

Taiwan’s Coast Guard said the merchant ships maintained normal navigation and were not boarded, inspected, or physically interfered with. A U.S. State Department spokesperson urged that differences be resolved “by peaceful means and free from coercion.”

Sources: Taiwan Coast Guard Administration via Reuters, Straits Times; China Taiwan Affairs Office via Xinhua; Statements by Taiwan Foreign Minister Lin Chia-lung