Air patrol exercise underscores Manila’s efforts to assert its maritime claims while testing US commitment to regional security, analysts say.

The Philippine coast guard says Chinese coast guard ships and a Chinese navy helicopter harassed a group of Philippine fisheries vessels conducting a scientific survey in a hotly disputed area of the South China Sea,

The Chinese military carried out combat readiness patrols in waters and airspace surrounding a hotly disputed Sea shoal on Friday, the latest in a series of exercises to reinforce its control of the area.

The air forces of the Philippines and the United States were holding joint patrols over the South China Sea on Tuesday, a spokesperson for the Philippine Air Force said, as Manila said it was monitoring three Chinese vessels in its maritime zones.

The Philippine military chief, Gen. Romeo Brawner, said at the time that the incident “posed a threat to Philippine air force aircraft and its crew, interfered with lawful flight operations in airspace within Philippine sovereignty and jurisdiction and contravened international law and regulations governing safety of aviation."

The Philippines launched a comic book on Friday in its fight against what it called distorted narratives about maritime rights in the disputed South China Sea, a move which drew criticism from China.

Earlier, Chinese naval vessels attracted Manila’s ire as they crossed Basilan Strait on the way to distant-sea training exercise.

The Philippines has launched a comic book to counter what the country says is China’s disinformation campaign to push its expansive territorial claims in the South China Sea