President Ferdinand Marcos Jr. said on Monday the presence of a Russian attack submarine in the Philippines' exclusive economic zone (EEZ) in the South China Sea was "very worrisome". "That's very concerning.

Philippine President Ferdinand Marcos Jr. said the presence of a Russian submarine in the Southeast Asian nation’s waters is “very concerning” as its military vowed to continue safeguarding its maritime sovereignty.

Tensions between Russia and the Philippines escalated as the Philippine military deployed a navy ship and air force planes to shadow a Russian submarine in the South China Sea last week, security officials said.

A Russian Kilo-class submarine identified as Ufa 490 was spotted within the Philippines' exclusive economic zone in the South China Sea. Philippine President Ferdinand Marcos Jr. expressed concern over the vessel’s presence,