A Philippine navy frigate was conducting a patrol near the disputed Scarborough Shoal in the South China Sea on June 20 when it was confronted and shadowed by four Chinese warships, the South China Morning Post reported on June 23. Both sides exchanged radio challenges and ordered the other to leave the area, though the Philippine ship completed its patrol without a reported collision or use of force.

Scarborough Shoal has been under de facto Chinese control since 2012. The shoal is near Luzon, the Philippines' most populous island, and is important to Philippine fishers, making it the site of a fishing grounds dispute and the most consequential direct pressure point on the Philippine mainland. The encounter followed several weeks of heightened activity around Scarborough Shoal, including Manila's diplomatic protest over a floating platform with an apparent antenna and Beijing's assertions that its activities there were lawful scientific research. It also came as the Philippines wrapped up military drills with the United States, Japan, Australia and New Zealand.