MANAMA, Bahrain – Senior American envoys challenged assertions Saturday that Washington seeks to diminish its role in Middle East affairs, insisting that American political ties and energy needs bind U.S. closely to the region.

The defensive tone by U.S. officials in response to questions raised at an international security summit in Bahrain reflects growing speculation about a possible U.S. policy realignment toward Asia at the expense of Mideast initiatives.

Gulf Arab states, in particular, have urged the Obama administration to take stronger action on Syria, where Saudi Arabia and Qatar seek to open channels to send heavy weapons to rebel forces fighting to oust Syrian President Bashar Assad. The White House has favored a more cautious approach with the Syrian opposition, worried that hard-line Islamist rebel factions could be aided by stepped up arms flow.