The Diet opened Monday amid expectations that the Abe administration will focus on security legislation to expand the overseas activities of the Self-Defense Forces after his Cabinet's decision last year to reinterpret the war-renouncing Constitution.

The 150-day ordinary session began with the government gripped by a hostage crisis in the Middle East that has apparently led to the execution of at least one of two Japanese being held by the Islamic State group. The crisis is bound to intensify the security debate.

Among the more controversial topics will be how to forge a legal framework to exercise the right to collective self-defense, or coming to the aid of an ally under armed attack.