Despite resistance from the Social Democratic Party and the Japanese Communist Party, the Diet passed a bill Friday to allow Self-Defense Forces commanders taking part in United Nations peacekeeping operations to order defensive fire if deemed necessary.

During a plenary session of the 252-seat Upper House, 161 lawmakers voted for the bill, with 30 voting against it.

Opponents, mainly SDP and JCP members, claimed the legal revision would violate the Constitution, which bans organized military activities abroad and the use of force to resolve international conflicts.

But members of the Liberal Democratic Party, the Democratic Party of Japan and others have supported the amendment to the law on U.N. peacekeeping missions, saying it is necessary to ensure the safety of SDF members.

The legal revision also aims to enable Japan to cooperate with international organizations, including the U.N. High Commissioner for Refugees, in extending supplies for humanitarian purposes, even in areas where war has broken out.

Under the original Law Concerning Cooperation for United Nations Peace Keeping Operations and Other Operations, the decision to use weapons fell under the individual judgment of members of a peacekeeping unit if a situation was deemed to be life-threatening.