BERLIN—German Chancellor Angela Merkel made a case to parliament for greater German participation in international conflicts, a day after her government's rare decision to ship antitank weaponry and small arms to Kurdish fighters in Iraq.

In a step away from its postwar pacifist traditions, Germany late Sunday announced plans to arm troops fighting Islamist insurgents. Although it doesn't legally have to, Berlin sought a parliamentary vote on the shipments, which lawmakers approved with a broad majority Monday.

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