The United States and South Korea have kicked off a major anti-submarine drill, weeks after North Korea claimed it had successfully tested a submarine-launched ballistic missile.
The South's Defense Ministry released a statement Monday, calling the drill "the largest joint anti-submarine exercise the allies have ever staged, in terms of its scale and number of vessels involved."
The exercise, which will run through Wednesday in waters off the southern resort island of Jeju, involves more than 10 vessels, including a South Korean Aegis destroyer, as well as submarines surveillance planes and helicopters.
The drills come amid growing concern about the expansion of the North's nuclear weapons and ballistic missile programs.