Members of Japan's Ground Self-Defense Force 1st Airborne Brigade take part in an annual new year military exercise in Funabashi, east of Tokyo January 13, 2013. Some 300 troops and 20 aircraft took part in the exercise. [Photo/Agencies]

TOKYO - Japan's Self-Defense Forces (SDF) launched a military drill on island defense in a training ground in the city of Narashino in Chiba Prefecture on Sunday.

The war game, which joined by Japan's only airborne force, was played under the assumption that a Japanese islet was captured by enemy and the airborne force re-took the island with the help of maritime and air forces.

Japanese Defense Minister Itsunori Onodera said after the drill that Japan's security circumstances worsened as its neighboring countries speeded up military modernization, especially after two rocket launches by the Democratic People's Republic of Korea.

He said the SDF must resolutely protect Japan's territories so as to protect Japan's public safety and people's lives.

About 20 aircrafts and 33 armored vehicles participated in the drill. The SDF planned to exercise a joint military drill with the United States in an island in Japan's Okinawa Prefecture but was canceled for strong opposition from local residents.