South Korea, U.S. start joint anti-submarine naval drill

South Korea and the United States have staged a joint anti-submarine naval drill to tackle North Korea's threats, sparked by the North's test-firing of a submarine-launched ballistic missile, the Navy said Monday.

The two allies kicked off the largest-ever combined anti-submarine exercise Saturday that will run through Wednesday in waters off South Korea's southern resort island of Jeju.

"The drill is aimed at deterring submarine-related provocations and beefing up the Navy's capacity to protect a southern maritime pathway, a key factor in maintaining operational logistics during war," the Navy said in a statement.

The exercise involves more than 10 vessels, including the Aegis destroyer Seoae Ryu Seong-ryong, two submarines and a P-8 Poseidon U.S. surveillance plane equipped with air-to-ground missiles, it added.

The five-day drill will include practical-level training based on diverse scenarios regarding Pyongyang's threats involving submarines, including tracing and identifying enemies' underwater capabilities and firing mines and bombs at them, according to the statement.

The move came after North Korea claimed last month that it had successfully test-fired a ballistic missile from a submarine in what could be a fresh threat to regional security. The North also said it has made nuclear warheads small enough to fit on missiles.

The allies began the biannual anti-submarine drills in 2012 as part of efforts to boost their underwater capabilities against threats from the North in the wake of its torpedoing of the South Korean warship Cheonan that killed 46 sailors.

"The exercise this time will be a chance to display a stern will that the allies' Navies will never tolerate North Korea's underwater provocations," said Nam Dong-woo, a one-star general that leads the program.

"The training will allow us to upgrade our anti-submarine multi-dimensional operations that involve maritime and airborne capabilities," he added.

North Korea is believed to have some 70 submarines, including about 20 1,800-ton Romeo-class vessels. It is also believed to be building a new submarine capable of firing missiles.