Correction: An earlier version of this story omitted the word "non-state" to describe those actors prohibited from receiveing Manpad transfers from the United States. Government-to-government transfers of Manpads are not prohibited.

More than two years since the uprising in Syria first erupted into a bloody conflict, the U.S. administration is weighing the costs and benefits of an intervention.

About 80,000 people have died in the clash between Syrian opposition fighters and the regime of President Bashar al-Assad. Food shortages are taking a serious toll on embattled civilians, as is a lack of medical supplies. Millions of people have been displaced by the fighting, both internally and abroad.

This week, the United States sent its first direct shipment of medical and food aid to the Free Syrian Army, the main opposition group. U.S. Secretary of State John Kerry said last month that Washington would double non-lethal aid to the opposition, to total $250 million.

But given the ongoing atrocities and the opportunity to weaken Assad allies such as Hezbollah and Iran, plenty of American politicians – including both hawks and doves – have urged stronger American action. President Barack Obama has said that the use of chemical weapons in Syria would mark a "red line" for the U.S., and administration officials have acknowledged that the evidence of such use is piling up.

Yet, nothing is certain; Obama’s red line has grown blurry in the fog of war. The president has stressed the importance of gathering evidence and rallying international support. Pinched by a budgetary crisis and dealing with the fallout from two massive wars, he's wary of engaging in yet another Middle Eastern conflict.

Providing arms to the rebels would be the least risky mode of intervention -- at least in the short term -- for any Americans involved, since it would require no U.S. troops on the ground or over Syrian airspace.

Arming the opposition carries serious consequences of its own. Islamist Syrian rebel groups have become increasingly influential in the Syrian uprising, and these include al-Qaeda linked outfits like Jabhat al-Nusra. If American-supplied weapons were to land in Syria, it would be nearly impossible to prevent those arms from falling into the hands of extremists – and that would have long-term implications for global security.

“That would be extremely problematic because it’s impossible to completely control the distribution and redistribution of weapons after they’re introduced into a theater like Syria,” Matt Schroeder, project director for arms trade research at the Federation of American Scientists, said.

That’s not to say American operatives haven’t already tried to steer weapons assistance into the right hands. Gulf states such as Saudi Arabia and Qatar are engaged in the disbursement of weapons to rebel forces, and reports have indicated the U.S. intelligence operatives are playing a key role on the sidelines.

In March, the New York Times cited U.S. officials who disclosed that CIA agents were acting as consultants from secret offices outside of Syria, helping to steer munitions purchased by Gulf states so that the weapons would end up benefiting more secular elements of the Syrian resistance.

There are also reports indicating that such efforts have failed to have much effect. Eliot Higgins, author of the widely-cited weapons analysis blog Brown Moses, has pointed to statements and videos showing extremist groups, including Jabhat al Nusra, using weapons of Yugoslavian origin, which were likely purchased from Croatian stockpiles by Gulf states or allies.

Clearly, alleged American involvement in these weapons transfers hasn’t eliminated the risks involved. But given the growing pressure to intervene more forcefully in the bloody Syrian conflict, Washington may still decide to ramp up its role in that capacity.

Not all military assistance has to be lethal; Salim Idriss, head of the Free Syrian Army's Supreme Military Council, has requested supplies including helmets, GPS tracking devices, armed vehicles and tranquilizer rifles.

Of course, deadly weapons are also on rebels' wish lists. Nic Jenzen-Jones, a munitions and security specialist and consultant based in Australia, notes that the opposition's needs have changed over the past several months.

“At this point in the conflict, small arms and light weapons are not as critical as they were earlier in the conflict,” he said.

“In the earlier days we saw rebel forces using civilian-type weapons, such as bolt-action hunting rifles and shotguns; there was a drastic need for more, and better, weapons. Now they've captured government arms, and we’re also seeing arms from former Yugoslavia, including anti-tank rocket launchers and recoilless guns.”

He added that some American rifles – M16s – are also present on Syrian soil, but these appear to have come from neighboring Lebanon, where they were supplied decades ago.

The rebels still face a definite shortage of weaponry, especially when compared to the well-armed regime forces who have the distinct advantage of air power. The opposition isn't as desperate for light arms as it once was and that will have to be considered if Washington decides to step in.

Exactly what sorts of weapons would America help to provide? According to Schroeder, that will hinge on the context.

“It depends on what items the groups need, what they are adequately supplied with and what types of systems they’re currently using,” he said. “For example if there’s a lot of Soviet originated equipment, which is likely, the spare parts would have to be for Soviet systems.”

That means the U.S. may help to purchase weapons and facilitate arms transfers, rather than supply weapons of its own.

If American-made munitions do make their way onto the battlefield, there’s a good chance they’d be older models.

“It’s possible the administration would see the value in providing additional anti-tank weapons, likely older systems by modern standards,” Jenzen-Jones said.

“If the US were looking to provide small arms, such as rifles, they would probably select AK-type rifles, or rifles chambered for 7.62x51mm, such as the FN FALs regularly seen in Syria, or similar rifles such as HK G3s.”

Older anti-tank weapons or rifles will help bolster the opposition, but realistically, they would have a hard time putting a dent in the regime’s air strike capabilities.

Unfortunately for the Syrian opposition, Washington is loath to supply tools that can take down aircraft – such as man-portable air defense systems, or Manpads, which are anti-aircraft missile launchers that can often be shoulder-mounted or else operated easily by a small team of fighters.

Manpads are the sort of weapons that could be seized by extremist elements of the opposition and turned against Western or allied forces down the road.

“There’s no way anyone could say with certainty that any Manpads would not be provided to parties hostile to the United States,” said Schroeder, adding that “the U.S. has agreed to several multilateral guidelines that proscribe the provisions of Manpads to non-state actors.”

Many of these regulations are vaguely worded enough to allow for exceptions, but Washington would be reluctant to overstep its bounds due to past experiences.

The most recent (officially acknowledged) parallel to Washington’s Syria quandary might be the U.S. decision to support Afghan rebels – the mujahedeen, who battled Soviet forces – during the 1980s under Presidents Jimmy Carter and Ronald Reagan. That assistance helped to empower militant groups that would later metamorphose into the Taliban and al-Qaeda.

Afghanistan remains a theater of war to this day; it is the type of conflict that makes the U.S. wary of stepping into the Syrian civil war. A Reuters/Ipsos poll released on Wednesday showed that 61 percent of Americans opposed any involvement.

Arming the rebels is only one of many options, but other methods of intervention carry greater risks.

Of these, targeted U.S. airstrikes have the most appeal since they could be carried out from bases outside the country, with limited endangerment of American lives. There’s also the option of a more comprehensive air campaign, which might require entering Syrian airspace and dealing directly with regime air forces and anti-aircraft weapons. In the most intense scenario, this might involve the establishment of a no-fly zone wherein rebels would be protected from regime airstrikes in the north, with help from NATO allies including Turkey.

Putting actual American combat troops on the ground in Syria is widely considered to be off the table.

Evidence of chemical weapons may change the diplomatic strategy of U.S. officials, but Washington will still be walking a very fine line as it settles on a course of action over the coming weeks.