Without a no-fly zone, the Syrian civil war will burn us all

As the grisly anatomy of the Boston bombings is laid bare, global attention is once again turning to the jihadist movement that spawned the attack.

Although this movement is a deadly force around the world - from Russia's Caucasus Mountains to Iraq, Nigeria and beyond - it has found a new rallying point: the bloody Syrian uprising.

With war-ravaged Syria becoming a hotspot for jihadist fighters and the Sunni-led rebellion drawing in thousands of foreign nationals, the Boston bombings show that the country's civil war is not just a threat to Syrians.

David Irvine, ASIO director-general, has warned that hundreds of Australians involved in the Syrian uprising could become 'severely radicalised' through exposure to 'extremist, al-Qaeda-type doctrines'.

This is far from fear mongering. As news emerges of a fourth Australian killed in Syria, the head of the Nusra Front, one of the leading rebel groups, has pledged allegiance to al-Qaeda and backed calls for an Islamic state in Syria.

Combined with the shocking humanitarian toll (more than 70,000 killed in just over two years), the growing jihadist infiltration of the uprising makes bringing the war to a speedy conclusion by imposing a no-fly zone essential.

The longer Bashar al-Assad's forces control the air, the longer the civil war will rage, which will further radicalise the uprising and turn Syria into a hub for transmitting battle-hardened jihadist ideology.

By rolling back Assad's domination of the air, a no-fly zone would also serve humanitarian goals: It would shield civilians from indiscriminate airstrikes and hasten the downfall of the oppressive Assad regime by giving the Free Syrian Army (FSA) tactical breathing space.

Initially, a no-fly zone may embolden the jihadists. With Damascus' air power neutralised, jihadists will probably redouble their efforts to influence the course of the rebellion.

It is, however, misleading to think that not intervening would allow the international community to sidestep the dangers posed by the rebellion's jihadist factions. In fact, withholding support for the uprising will only prolong the bloodshed and amplify the radicalisation.

Even without the international community's assistance, arms and cash from the Arabian Peninsula are being funnelled to the rebels via Turkey. A well-armed and funded uprising, combined with Assad's steadfast grip on power, means that the civil war could grind on for months or even years.

As well as killing tens of thousands of Syrians, a prolonged conflict would mean more fighters joining the fray from jihadist flashpoints such as the North Caucasus region, Iraq and Afghanistan.

On top of fuelling sectarian tensions and endangering Syria's democratic transition, a large jihadist presence raises the terrifying prospect of Assad's chemical and biological weapons falling into the hands of al-Qaeda-affiliated groups.

The obvious obstacle to a no-fly zone is resistance from Russia and China in the United Nations Security Council (UNSC). The mission creep that followed their abstentions on the UNSC resolution authorising the Libyan no-fly zone left a bitter taste for these veto-wielding, anti-interventionist world powers.

The historically close ties between Moscow and Damascus make getting movement on a no-fly zone even harder.

Russia is heavily invested in the survival of the Assad regime. The Russian naval facility at Tartus on the Mediterranean coast is the only base of its kind beyond the territory of the former Soviet Union, and Syria was Russia's second-largest arms customer in 2011.

Nevertheless, the Syrian equation is now also changing for Russia.

Despite the Assad regime's determined fight for survival, the fall of Damascus is more a question of when, not if. The regime has lost control of much of Syria's frontier with Iraq and the Kurdish north-eastern regions, while rebels are advancing in the southern province of Daraa.

The likely eventual collapse of the beleaguered Assad regime means that Russia stands to gain little from continuing its support. Even if Moscow throws its full diplomatic weight behind Damascus, it will probably still lose its partner, while also earning the ire of the new Syrian government.

For Russia, the Syrian calculation is clear. Lose Assad now and save a little face, or lose him later and face opprobrium.

Even if Russian and Chinese support for a no-fly zone can be won, the international community's options remain diabolical: non-intervention and an unrelenting civil war that leaves tens of thousands more civilians dead and traumatised, or a no-fly zone and regime change that could precipitate brutal reprisals against Assad's Alawite backers and the rise of an authoritarian Islamist state.

As grim as these Syrian scenarios might be, it is delusional to expect foreign policy dilemmas this serious to offer easy choices.

Instead of wishing the world was different, it is time for the international community to take a calculated risk, accept part of the burden of responsibility for regime change in Damascus, and impose a no-fly zone.