Washington â€"  As one diplomatic effort after another fails to end more than a year of brutal violence in Syria, the Obama administration is preparing a plan that would essentially give U.S. nods of approval to arms transfers from Arab nations to some Syrian opposition fighters.

The effort, U.S. officials told The Associated Press, would vet members of the Free Syrian Army and other groups to determine whether they are suitable recipients of munitions to fight the Assad government and to ensure that weapons don't wind up in the hands of Al Qaeda-linked terrorists or other extremist groups such as Hezbollah that could target Israel.

The plan, which has not yet been finalized, reflects U.S. frustration that none of the previous efforts -- including diplomatic rhetoric from the United Nations and the multinational Friends of Syria group, and special envoy Kofi Annan's plan for a cease-fire -- has even begun to nudge President Bashar al-Assad from power. The vetting would be the first tiny step the U.S. has made toward ensuring that the Syrian opposition uses the weapons to fight Assad and not to turn it into a full sectarian conflict.

While some intelligence analysts worry that there may be no suitable recipients of lethal aid in the Syria conflict, the vetting plan has arisen as the least objectionable idea in a complicated situation.

U.S. officials, most of whom spoke on condition of anonymity because of the sensitive nature of the subject, stressed that the United States, which is already providing non-lethal aid to Syria's political opposition, is not supplying military assistance to Assad's foes.

The administration's position remains that adding more weapons to the conflict is a bad idea and will only fan the fire of instability.

"We don't think that adding fuel to this fire is the right way to go," State Department spokeswoman Victoria Nuland said.

"Our decision is to support the civilian opposition in nonlethal ways," she said. "There are other countries who have made other decisions. That's their sovereign decision to make. We've made our decision."

But she added: "We are obviously consulting with various states about the decisions that we've made, that they've made."

Privately, officials say that as conditions continue to deteriorate, it would be irresponsible not to weigh in with Arab countries such as Saudi Arabia, Qatar, the United Arab Emirates and others such as Turkey that have indicated interest in arming the rebels.

By some accounts, those nations already have begun to ship weapons with tacit U.S. agreement. In Turkey, private businessmen have begun funneling weapons into Syria.

Libya's new rulers, fresh from their own revolution that toppled longtime dictator Moammar Gadhafi, have pledged support for the Syrian rebels, but actually transferring weapons is tricky. Last month, Lebanese authorities seized a ship carrying rocket-propelled grenades and heavy-caliber ammunition, possibly bound for Syrian rebels.

The fighters' attempts to bring in heavier arms that could change the course of the 15-month-old uprising so far have been stymied at every turn, even by countries sympathetic to the revolt. All are wary of being drawn into the fight

The rebels have cast a wide net, contacting weapons dealers in Bulgaria, Greece, Georgia and Azerbaijan.

Without some type of U.S. vetting as to who should receive such shipments, the Obama administration and some of its European allies fear that weapons might be used against Western interests.

While the "main" Syrian opposition is not aligned with Al Qaeda, the chance that weapons might fall into the wrong hands in an unstable environment like Syria is "always a concern," said a senior intelligence official.

Al Qaeda has established a limited operational capability in Syria and is responsible for several attacks on Assad targets, the official said. He said analysts believe the goal is to "sow further chaos" and advance an extremist agenda.

The official would not comment on any military aid that might be given to the rebels by U.S. allies.

Yet he and others acknowledged the situation is growing more dire.

AP interviews with security officials, rebels and arms dealers in countries neighboring Syria indicate that individual rebel units have to scrounge for weapons. They have no central organization and no import routes for anything heavier than automatic weapons and rocket-propelled grenades.

It is into this mix that the U.S. may soon be inserting itself.

Washington's supplies of communications equipment and medical supplies to opposition members it has approved are already under way, Officials said that those supplies can now be easily augmented with weapons from other donors.

"Smuggling lines are smuggling lines. We use the same donkeys," said one, pointing out that the routes are essentially the same for bandages as they are for bullets.