If the ceasefire in Syria is to hold, this is what needs to happen

One of several problems is that the most important armed force on the non-Isis rebel side, Jabhat al-Nusra, is expected to obey a ceasefire from which it is excluded and under which it will shortly be targeted

A member of the Syrian pro-government forces carries an Isis flag in Palmyra on 27 March 2016 (Getty)

Suicide bombers are central to a new style of warfare that has emerged during the Iraq, Afghan and Syrian wars and is shaping political and military developments across the world. The tactic is effective because it turns thousands of untrained religious fanatics – most of whom come from the Salafi-jihadi variant of Islam – into devastating weapons of war. All the bomber needs is a willingness to die.

What is different about suicide bombing in the wars currently being fought in the Middle East and beyond, is that the bombers are skilfully deployed in great numbers. The impact of many individuals wearing explosive vests or driving vehicles packed with explosives on the battlefield can counter-balance the other side’s control of the air and superiority in heavy weapons. For instance, when Isis forces were trying to capture the last government strongholds in Ramadi, the capital of Anbar province, in May last year, it sent 10 bombers driving specially armoured Humvees to blast their way through the fortifications.

The devastating effectiveness of suicide bombing is relevant to the prospects for the current ceasefire in Syria and the plan for the US and Russian air forces to launch attacks on Isis and Jabhat al-Nusra, formally the Syrian branch of al-Qaeda that has renamed itself Jabhat Fateh al-Sham. More "moderate" armed rebel groups are meant to move away from Nusra forces so they can be targeted, though it is more likely that the Jihadis would offer their comrades-in-arms a choice between solidarity with them or death

Observers in Damascus point out that the non-Isis armed opposition in Syria is dominated by Nusra fighters, saying that “without Nusra the non-Isis armed opposition would be very weak. Nusra has led all the successful rebel offensive against the Syrian army. It has overcome any rebel opponents who resisted it in a matter of days.” Nusra has no incentive to maintain a ceasefire directed against itself and every reason to see it fail.

The very existence of a “moderate” armed opposition of any strength inside Syria has always been a matter of wishful thinking by Western leaders. Some intelligence agencies were aware of this from an early stage, but they were either ignored or governments did not really care who they were backing in trying to displace President Bashar al-Assad. As early as August 2012, the Defence Intelligence Agency, the Pentagon’s intelligence arm, had written a report which firmly stated: “The Salafists, the Muslim Brotherhood, and AQI [al-Qaeda in Iraq] are the major forces driving the insurgency in Syria.”

Several cogent explanations have been given for the dominance of Salafi-jihadi movements such as Isis and Nusra in the Sunni Arab armed opposition in Iraq and Syria. These include their ideological commitment, their ferocity and their support from Sunni states such as Turkey, Saudi Arabia and Qatar. But there is an additional reason seldom mentioned why Isis and Nusra, and some allied movements, have become the chief fighting arms of a Sunni Arab insurrection in both countries. They alone can recruit and motivate the thousands of suicide bombers who, over the years, have enabled them to fight and, on occasions, to overcome the Syrian and Iraqi armies, despite their air support and artillery. The use of suicide bombers does not guarantee success or necessarily avert defeat, but it does give Isis and Nusra a fighting chance against their enemies. Even where they fail to break through, the precautions necessary to stop them – like getting bulldozers to dig a deep trench in advance of the front line as happened earlier this year outside Mosul during a small advance by the Iraqi Kurdish Peshmerga – slows down the enemy.

Suicide bombing is not new. I first encountered it in Damascus in about 1980 when Muslim Brotherhood militants were occasionally driving vehicles filled with explosives into government buildings. Massive concrete flower tubs were placed in the streets to stop vehicles getting close to potential targets. More spectacularly, Shia suicide bombers belonging to the precursor of Hezbollah in Lebanon blew up the US embassy in Beirut in 1983 and, some months later, destroyed the US Marine barracks by the airport where 242 Marines were killed. The blast was powerful enough to blow out the supporting concrete columns so the floors pancaked on top of each other.

Al-Qaeda integrated into their ideology the idea of suicide attacks as a public demonstration of Islamic faith by the perpetrator, the most infamous instance of this being the hijacking of planes and crashing them into the World Trade Centre and Pentagon on 9/11. Soon after the US invasion of Iraq in 2003, there were multiple suicide attacks that rapidly took away the initiative from the US military, greatly superior though it was to the insurgents in terms of numbers, training and equipment. But it was only with the re-emergence of what was to become Isis in Iraq from about 2011, and its offspring Nusra in Syria from 2012, that suicide bombing was lethally combined with traditional infantry tactics such as IEDs (Improvised Explosive Devices), booby traps, snipers and mortar teams.

Does this mean that the US-Russian agreement on 10 September – on a ceasefire, aid convoys to besieged cities and a joint campaign against Nusra and Isis – is bound to fail? Not really, though it is important to realise that the peace plan is coupled with a war plan and the two contradict each other. One of several problems is that the most important armed force on the non-Isis rebel side, Nusra, is expected to obey a ceasefire from which it is excluded and under which it will shortly be targeted.

These contradictions might be overcome if the US and Russia continue their efforts to implement the agreement with the same determination with which they negotiated it. They need to do so because both must pressure their allies and proxies in the region – the Syrian government, Iran, Hezbollah in the case of the Russians and Turkey, Saudi Arabia and Qatar in the case of the US – not to covertly undermine the accord. If put under enough pressure, none of the parties on the ground in Syria can ignore their outside backers.

There is a further difficulty facing the implementation of the agreement: This is its lack of institutional and media support in the US where Secretary of State John Kerry had to defend it against aggressive questioning by, among many others, NPR which cited open scepticism in the Pentagon. Kerry emphasised that President Obama had signed off on the agreement and that there was no alternative to it except an escalating war. He rightly said that the grim alternative to the accord “is to allow us to get from 450,000 people, who’ve been slaughtered, to how many thousands more? That Aleppo gets completely overrun? That the Russians and Assad simply bomb indiscriminately for days to come and we sit there and do nothing?” What is so culpable in the case of US and European critics of the accord is that they offer no practical alternative to it and, while pretending humanitarian concerns, accept that the present horrors should continue.