This photo provided by the South Korean Navy on Oct. 3, shows the ROKS Marado, front, and the USS Boxer, amphibious assault ships participating in a combined South Korea-U.S. marine exercise in the East Sea the previous day. Yonhap

South Korea and the United States have completed a combined marine exercise in the East Sea to strengthen their interoperability, the South's Navy said Thursday.

The two navies held a two-day exercise, starting Wednesday, in waters off Pohang, some 270 kilometers southeast of Seoul, involving four naval vessels, including the ROKS Marado and the USS Boxer, both amphibious assault ships.

A Wasp-class ship, the USS Boxer can carry about 40 aircraft, including F-35B stealth fighters. The 40,500-ton ship also took part in the Exercise Ssang Yong involving the South Korean and the U.S. Navies and Marines.

"The two navies will improve our ability to carry out combined operations and interoperability, and sternly respond to any form of provocations from the enemy," said Capt. Kim Kyung-ho, commodore of Amphibious Squadron 53 of the South Korean Navy. (Yonhap)