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.