In an escalation of simmering tensions in East Asia, South Korea said Sunday that it was expanding its air patrols further into the East China Sea.

The move to expand its air defense identification zone (ADIZ) comes just a week after China said it was expanding its patrols to cover disputed islets that are also claimed by South Korea and Japan.

South Korea said that it was expanding the ADIZ to cover portions of the sea known as "leodo" which is also claimed by China and Japan.

The reef is said to potentially contain minderal and natural gas deposits. It is currently under the control of South Korea but China claims it.

South Korea's new ADIZ overlaps slightly with China's recently declared zone.

The northeast Asian nation said that the announcement would go into effect next week.

Neither Japan nor China has commented on the move.

Territorial disputes in East Asia have been on the rise lately, particularly as China seeks to expand its control over the East China Sea.

The United States was said to be aware of South Korea's expansion. A State Department statement read:

“We also appreciate [South Korea’s] commitment to implement this adjustment to its ADIZ in a manner consistent with international practice and respect for the freedom of overflight and other internationally lawful uses of international airspace,” the statement said.