In one memorable scene in David Lean’s masterful Lawrence of Arabia, Lawrence has returned to General Allenby’s Cairo headquarters. He is exuberant. He and some Arab tribes have liberated the port of Aqaba from the Turks. Lawrence wants to return to the desert to continue the rebellion, but tells Allenby he needs many items for the Arabs. “Two thousand small arms not enough. I need five; Money. It’ll have to be sovereigns. They don’t like paper; Instructors for the Lewis guns; More money; A couple of armoured cars…and field artillery.” Allenby pauses, but responds “I’m going to give you every blessed thing I can Major Lawrence, because I know you’ll use it.” Allenby is then confronted by his senior political and military advisors:

“Are you really going to give them artillery, sir?”

“Might be deuced difficult to get it back again.”

“Give them artillery and you’ve made them independent.”

Allenby concurs: “Then I can’t give them artillery, can I?”

The dilemma surrounding what weapons to provide the anti-Assad forces fighting in Syria is equally difficult. The most effective weapon to give them on such short notice would be the man-portable air defense systems (MANPADS) that could be used to shoot down aircraft and helicopters and thus help deter the Syrian army’s advances towards key rebel-held areas. These could include the formidable Stinger missile, which the United States provided to the mujahideen in Afghanistan and that contributed to making life so unpleasant for the Soviet forces. But we now know that once a Stinger missile has been transferred, it is very difficult to retrieve. Man-portable missiles also pose a serious threat to civil aviation around the world.

The tradeoff has to be providing weapons that are effective in the current conflict but not too dangerous if they fall into the wrong hands. So far, rebel pleas have understandably centered on antiair missile systems and other heavy weapons, citing Assad’s airborne and vehicular advantage as responsible for loss of ground in recent months. But while such arms certainly might prove most effective in helping turn the tide of battle in Syria, there are other, less dangerous ways to bolster the strength of rebel forces in the near term.

First, heavy machine guns and munitions could be delivered quickly and effectively to Syria to help rebel forces balance the Assad regime’s ability to attack by air. A limited supply of Russian-made heavy guns have already had a significant impact on the battlefield, and American weapons would immediately increase the rebel capacity to deter helicopter support to Assad’s ground forces and secure local airspace. Though not as effective as missiles, big caliber guns can threaten ground-attack fighters, particularly since the Syrian Air Force lacks significant guided munitions and must operate at low altitudes during combat.

Second, many more antitank missiles could be introduced into Syria through various routes and would help rebels fight the hundreds of armored tanks and other vehicles currently being used by the Assad regime, particularly near Aleppo. A small number of AT-5 Konkurs systems delivered by Saudi Arabia have already proven to be effective battlefield equalizers for anti-Assad forces and more would help ground units compete. When it comes to the postconflict risks, antitank missiles are not significantly more worrying than commonplace rocket-propelled grenades.

Any delivery of arms, munitions or expertise could also focus significantly on matériel that will improve the survivability of Syrian rebel forces, rather than just their offensive capabilities. Coordination with Gulf Arab countries on providing Russian-made small arms and ammunition, in addition to making any aid intervention seem more politically international in nature, would undoubtedly allow for greater consistency in the weapons available to rebel forces and reduce the logistical issues that will come with the transition to foreign sources of aid. Delivery of protective combat wear, surveillance and communications gear and other ancillary equipment would also let anti-Assad units operate with greater security and cohesion moving forward and might help rebel leadership better expend their limited resources.

The other dilemma, of course, is that the most effective forces fighting Assad are those Al Qaeda associates that the United States and its partners do not want to see in strong positions in Syria if Assad falls. In addition to providing smart aid, U.S. strategy must make sure that the anti–Al Qaeda elements are organized, trained and disciplined enough to use the types of weapons we could provide, and that some institutional check is in place to ensure that they will not fall into the wrong hands.

In reality, full control over the weapons cannot be guaranteed. Thus policy makers must consider how important is it to defeat Assad and Hezbollah and run the risk that bad guys will take over. This certainly has not been addressed in any formal way by the Obama administration’s on-again, off-again policy towards the uprising. But it’s a tough call.

To allow Iran and Hezbollah, along with Assad, to obtain victory is unacceptable. To force a long war of attrition, with neither side achieving a clear victory, may be the best we can hope for at this time. There are some suggestions that Hezbollah and Iran are getting sucked into a Stalingrad situation in the major city of Aleppo, where they clearly have firepower dominance. But if the rebels are provided with sufficient arms, the pro-Assad forces will be tied down for many months, during which casualties will soar and begin to erode Hezbollah morale, weakening their overall position in Lebanon.

With that in mind, a more serious discussion with Congress on the costs and benefits of what weapons are to be provided to the Syrian rebels must be pursued by the administration with no illusions as to the dangers.

Geoffrey Kemp is the director of Regional Strategic Programs at the Center for the National Interest. Christopher Whyte is a WSD-Handa Fellow at CSIS Pacific Forum and an analyst for the geostrategic analytic firm Wikistrat, Ltd.