In the latest sign of Manila being determined to ratchet up tensions in the South China Sea, the Philippines sent coast guard vessels and other ships into the waters adjacent to Ren'ai Reef of China's Nansha Islands to deliver construction materials and other supplies to an illegally "stranded" warship there. This happened despite repeated warnings from the China Coast Guard to the Philippines to not violate China's maritime sovereignty.

China has indisputable sovereignty over the Nansha Islands, including Ren'ai Reef, and their adjacent waters. The warship, which the Philippine Navy illegally grounded in 1999 on the false excuse of a "malfunction", should have long been removed from the Chinese reef based on an agreement between the two governments. But Manila has reneged on its promise and instead tried to consolidate the shipwreck's presence on the reef by turning it into a more permanent installation. This leaves the China Coast Guard no choice but to intercept any Philippine vessels attempting to send construction materials to the illegally grounded vessel in accordance with the law.

During their activities on Sunday, the Philippine vessels acted in an unprofessional and dangerous manner in violation of international maritime regulations, which led to collisions with Chinese vessels. The maneuvers by the Philippine side risked lives and violated the Declaration on the Conduct of Parties in the South China Sea. The Philippine side bears full responsibility for what transpired.

However, in a typical case of a thief crying "catch the thief", Manila summoned the Chinese ambassador to lodge a protest against China's "aggressive" actions. This, in addition to the reckless actions of the Philippine vessels, risks plunging bilateral friendly relationship over the precipice into conflict.

For years China and the Philippines have basically kept the development of their mutually beneficial relations stable by exercising restraint, defusing tensions and working on a mutually agreed framework for cooperation. As a result, they, together with other regional countries, have been able to maintain peace, security and stability in the South China Sea despite the territorial disputes.

Yet after Philippine President Ferdinand Marcos Jr took office in June last year, bilateral relations have been on a downward spiral, mainly due to the Philippine leader trying to bind the country to the United States' geopolitical bandwagon. He not only invited US troops back to the Philippines in February, but has also pushed for joint military drills with the US in the South China Sea targeting China. The strengthened alliance with Washington, as well as the latter's promise to come to its aid under a mutual defense treaty, has obviously given Manila the audacity to make provocative moves against China in the South China Sea.

Manila is needlessly playing with fire. It should stop before it is too late.