The Maritime Self-Defense Force and the Japan Coast Guard are planning their first joint drill for a "gray zone" incident that would stop short of a military attack on Japan, according to a government source.

The drill will be held "soon" near Izu Oshima Island, about 120 km south of Tokyo, the source said Monday.

The Coast Guard will first determine the locations, speed and number of intruding vessels and share information with the MSDF, which will take over and intercept the vessels, according to the source.

Chinese vessels have been frequently intruding into Japan's territorial waters around the Senkaku Islands in the East China Sea.

The drill could draw criticism from China as the Japanese and Chinese governments are making arrangements to sign an agreement as early as this month to set up a maritime communications mechanism to avert accidental clashes in the East China Sea.

The exercise is seen as part of Prime Minister Shinzo Abe's drive to bolster Japan's defense capabilities and the role of the Self-Defense Forces both at home and abroad.

In the controversial security bills currently under Diet deliberations, the government is eying a system of giving Cabinet approval by phone for swift SDF dispatch to cope with gray zone incidents, including an attempt by an armed group disguised as fishermen to take control of a remote Japanese island.