Japan is to send an escort ship and a PC3 patrol aircraft to a Proliferation Security Initiative exercise to be staged at Busan Port and nearby on Oct. 13-14.

This will be the first PSI exercise to be staged at South Korea's initiative since Seoul joined the U.S.-led alliance after North Korea's second nuclear test in May last year.

The U.S., Australia, New Zealand and Singapore will also participate in the interdiction and search exercise aimed at preventing the spread of so-called weapons of mass destruction.

Japan is taking part not in a bilateral exercise but a multinational military drill, Tokyo said. However, observers note that this is the first time Japan's Maritime Self-Defense Force has taken part in an exercise in the South Korean territorial waters. Japan joined in a PSI exercise led by Singapore in October last year.

Seoul and Tokyo are also considering an agreement on mutual supply of goods and services when engaged in UN peacekeeping activities.