South Korea and the United States Marines Corps. will intensify their joint amphibious drill in March, an official familiar with the matter said Sunday, in what could be seen as a retaliation against the recent nuclear test and long-range rocket launch by North Korea.

The two Marines will strengthen their inland ground operations, which are conducted after landing in an amphibious vehicle, a South Korean military official told Yonhap News Agency on condition of anonymity.

The two allies will try to boost their capability to infiltrate deep into North Korean territory and destroy the North's key facilities, such as its nuclear and missile test sites, the official said.

The two countries will double the period of the exercise and widen the area covered from last year.

The drill will involve some 10,000 South Korean sailors and 7,000 U.S. ones, the largest scale since the drill, known as Ssangyong, was launched in 2012.

The exercise will employ a Bell Boeing V-22 Osprey, an American multi-mission aircraft that can take off and land vertically, and the New Orleans, an American amphibious warfare ship.

The Marine drill fits into the broader scheme of the annual Key Resolve and Foal Eagle exercises to be conducted next month.

Tensions have soared on the Korean Peninsula in recent weeks over North Korea's nuclear test and long-range rocket launch.

South Korea has joined the United States and other regional powers in pushing for tightened U.N. sanctions on North Korea for its latest provocations. (Yonhap)