The rare overseas deployment, which will be limited to intelligence-gathering, is meant to ensure the “security” of Japanese merchant ships and help maintain “peace and stability” in the region, the cabinet office said in a statement.
The decision follows a series of attacks on oil tankers in the region, one of which was Japanese-operated.
The deployment will include one destroyer, equipped with helicopters, and at least one of two P-3C patrol planes currently engaged in antipiracy operations near Somalia.
The mission has been authorized for one year and can be extended.
The announcement follows a meeting last week in Tokyo between Prime Minister Shinzo Abe and President Hassan Rouhani of Iran, whose country the United States has blamed for attacks on tankers in the Gulf of Oman in June.
The United States has called for an international coalition to protect ships in the region, but only a few of its allies have joined that mission.