The Armed Forces of the Philippines (AFP) monitored 18 Chinese military and coast guard vessels in the West Philippine Sea over the past week, a military spokesperson said Tuesday.

Rear Adm. Roy Vincent Trinidad (ret.), the military spokesperson for the West Philippine Sea, said the deployment included People’s Liberation Army Navy and China Coast Guard vessels spotted between 4 and 10 August.

Trinidad said eight Chinese Coast Guard ships were tracked near Ayungin Shoal, also known as Second Thomas Shoal, while one Chinese navy ship and seven coast guard vessels were monitored around Bajo de Masinloc, also known as Scarborough Shoal.

Single coast guard vessels were also detected near Escoda Shoal and Pag-asa Island, Trinidad added.

The latest tracking follows a total of 48 Chinese vessels monitored in the area during July.

Tensions in the region remain high as Beijing claims nearly the entire South China Sea, a critical waterway for more than $3 trillion in annual commerce, despite overlapping claims by the Philippines, Vietnam, Indonesia, Malaysia and Brunei.

The Philippines uses the term West Philippine Sea to designate the portion of the South China Sea that falls within its exclusive economic zone, including the Luzon Sea and waters surrounding the Kalayaan Island Group and Scarborough Shoal.

In 2016, an international arbitration tribunal in The Hague ruled that China’s sweeping historical claims over the waterway had no legal basis under international law, a decision Beijing continues to reject.