RIYADH, Saudi Arabia (AP) — The Obama administration is considering allowing shipments of new air defense systems to Syrian rebels, a U.S. official said Friday.

President Barack Obama's possible shift would likely be welcomed by Saudi Arabia, which has been pressing the White House to allow the man-portable air-defense systems, known as "manpads," into Syria. Obama arrived in Saudi Arabia on Friday evening for meetings with King Abdullah.

Allowing manpads to be delivered to Syrian rebels would mark a shift in strategy for the U.S., which until this point has limited its lethal assistance to small weapons and ammunition, as well as humanitarian aid. The U.S. has been grappling for ways to boost the rebels, who have lost ground in recent months, allowing Syrian President Bashar Assad to regain a tighter grip on the war-torn nation.

The actual manpad shipments could come from the Saudis, who have so far held off sending in the equipment because of U.S. opposition.

The president is not expected to announce a final decision on the matter during his overnight trip to the Gulf kingdom. U.S. and Saudi intelligence officials have been discussing the possibility of injecting manpads into the crisis for some time, including during a meeting in Washington earlier this year.

As recently as February, the administration had said Obama remained opposed to any shipments of manpads to the Syrian opposition. The U.S. has been concerned that the weaponry could fall into the wrong hands and possibly be used to shoot down a commercial airliner.

Among the reasons for Obama's shift in thinking is the greater understanding the U.S. now has about the composition of the Syrian rebels, the official said. However, the official added, the president continues to have concerns about escalating the fire power on the ground in Syria, which has been torn apart by more than three years of civil war.

The official wasn't authorized to discuss the internal deliberations by name and insisted on anonymity.

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