WASHINGTON: US lawmakers voted Wednesday to authorize training and arming of vetted Syrian rebels to combat Islamist radicals, a crucial step in President Barack Obama's bid to thwart extremism surging across Iraq and Syria.

Despite misgivings by war-weary Democrats that the move could open the door to full-blown American military intervention in the Middle East, and concern by conservatives that the plan falls short of what is needed to defeat the Islamic State group, the House of Representatives voted 273 to 156 to approve Obama's train-and-equip plan.