The Philippine Coast Guard said it deployed aircraft on May 7, 2026, to issue radio warnings to the Chinese research vessel Xiang Yang Hong 33, which was conducting unauthorized marine scientific research near Iroquois Reef in the disputed Spratly Islands. The vessel was observed deploying a service boat toward the reef, an area within the Philippines' exclusive economic zone but claimed by Beijing.

Philippine officials reported that 41 Chinese maritime militia vessels were anchored near Iroquois Reef and Thitu Island, where approximately 400 Filipinos reside and a new coast guard station operates. The Coast Guard stated the Philippines had not granted China permission for any scientific research in the area, calling the activities a serious infringement of its sovereign rights and maritime jurisdiction.

China's Embassy in Manila responded by asserting its 'historic rights' over the South China Sea, claiming the islands and reefs in question are Chinese territory. It maintained that the Xiang Yang Hong 33's operations were conducted in accordance with international law.

The Xiang Yang Hong 33 has been tracking near multiple Philippine-claimed features in the Spratlys since departing China over three weeks ago, including Sabina Shoal and Second Thomas Shoal. China continues to enforce its expansive South China Sea claims through coordinated deployments of naval, coast guard, and maritime militia vessels.

The Philippine government is expected to raise the issue through diplomatic channels, while monitoring continues for further movements. The United Nations Convention on the Law of the Sea (UNCLOS) arbitration ruling from 2016, which invalidated China's broad claims, remains a point of contention in ongoing maritime disputes.