The South Korean Navy, Japan's Maritime Self-Defense Force and the US Navy have staged a joint missile-defense exercise in international waters south of the Korean Peninsula.

South Korea's Defense Ministry says participants in Tuesday's drill carried out ballistic-missile tracking and information-sharing procedures, based on a scenario in which North Korea has fired a missile.

It says the exercise was in response to the heightening threat posed by North Korea, including last week's attempt to launch what Pyongyang claimed to be a military satellite.

An image released by the South Korean defense ministry showed three Aegis destroyers -- one from each country -- navigating side by side.

The ministry says the three countries tested a real-time information sharing system for missile launches. They plan to deploy the system by the end of the year.

It also says the three countries will work together to strengthen their readiness and capabilities to counter the threat posed by North Korea's nuclear and missile programs.