Philippines Alleges China Used Cyanide in South China Sea

The Philippines has made a grave accusation against China, claiming that Chinese boats were found with cyanide near the disputed Second Thomas Shoal in the South China Sea. Laboratory tests confirmed the presence of the toxic substance in bottles seized by the Philippine navy last year.

Security officials warned that the cyanide could have severe consequences for marine life and potentially weaken the reef that supports a warship Manila grounded on the atoll to reinforce its maritime claim. The use of cyanide is seen as a form of sabotage aimed at killing local fish populations and depriving navy personnel of a vital food source.

Cornelio Valencia, spokesperson for the National Security Council, emphasized that the cyanide could damage the reef and compromise the stability of the warship. In response, China's Foreign Ministry dismissed the Philippines' assertions as a 'stunt,' accusing Manila of illegally harassing Chinese fishing boats and staging the incident.

The incident is part of a broader maritime dispute between China and the Philippines, with China claiming nearly all of the South China Sea, including areas claimed by other nations. The dispute has led to several confrontations, including a violent incident on June 17, 2024, where a Filipino sailor lost a finger. The Philippines also accused Chinese coastguard ships of firing water cannons at Filipino fishermen in December 2025, injuring three people and damaging two fishing vessels.

Despite these tensions, China and the Philippines held high-level talks last month to explore preliminary steps towards oil and gas cooperation and confidence-building measures at sea. However, the Philippine Foreign Ministry noted that the scope of coastguard cooperation would be limited and did not include joint patrols.

The South China Sea is a critical waterway, with over $3 trillion in annual ship-borne commerce traveling through it. A 2016 ruling by an international arbitral tribunal found China's sweeping claims had no basis under international law, a decision China rejects.