Japan and the United States are making arrangements to revise the two nations' defense cooperation guidelines in late April before Prime Minister Shinzo Abe's planned trip to the United States, sources knowledgeable about Japan-U.S. relations said on Wednesday.

The defense guidelines delineate the roles of the U.S. military and Japan's Self-Defense Forces in joint operations. Their revision is expected to be decided at a meeting of the two countries' foreign and defense ministers in Washington, the sources said.

The revised guidelines are expected to include a larger scope of action for the SDF, based on last year's contentious decision to reinterpret the pacifist Constitution to enable the exercise of the right to collective self-defense, or defending allies under armed attack.