It’s time for Britain and its allies to take concerted, sustained military action to curb Bashar al-Assad’s ability to murder Syria’s citizens at will. Before hands are thrown up in horror at the prospect of another open-ended, armed western intervention in the Middle East, consider the following. Since 2011, when the uprising against Assad’s regime descended into civil war, nothing has worked. As the toll has risen inexorably towards 500,000 dead, the United Nations has tried ceasefires, truces, pauses, local talks and national negotiations. All have fallen apart.

As millions of civilians fled, or were trapped, the EU and others proposed refugee quotas, safe havens, humanitarian corridors, no-fly areas and de-escalation zones. None has succeeded in staunching the flow of blood and misery. And Assad is not finished. Next up is rebel-controlled Idlib province, where millions cower in terror, awaiting their turn.

Calls to wait for yet another UN investigation amount to irresponsible obfuscation

When Assad used illegal chemical weapons in the past, most notoriously in eastern Ghouta where up to 1,700 people died in a 2013 sarin nerve gas attack, the US failed to enforce what Barack Obama called a red line. Obama was undoubtedly influenced by the British parliament’s vote against military action in August that year. Since then, ignoring Russia’s worthless guarantees, the regime has used chemical weapons, including mustard gas, again and again – culminating in Saturday’s horrific chlorine attack in Douma. Last year, Donald Trump was so upset by photos of gassed children, he ordered a limited missile strike. Assad shrugged it off. Trump should know better now. One feel-good bomb-fest does not a strategy make.

And before anybody claims chlorine gas is not the same as a highly toxic nerve agent, note that the Organisation for the Prohibition of Chemical Weapons (OPCW), about which we have heard a lot lately, holds that “any chemical” repurposed for an attack “is considered a chemical weapon by the [1997 chemical weapons] convention”.

Calls to wait for yet another UN investigation amount to irresponsible obfuscation. Only the Syrian regime and its Russian backers have the assets and the motivation to launch such merciless attacks on civilian targets. Or did all those writhing children imagine the gas?

Such investigations get nowhere in the Syrian context. Last April, the OPCW-UN joint investigative mechanism attributed the Khan Shaykhun atrocity to the regime. But when the UN security council met to condemn it, Russia vetoed the resolution – as it does repeatedly on Syria.

Western countries have already intervened militarily since 2011, of course, but largely for their own purposes. Britain’s main interest is extirpating Islamic State forces. The US has cautiously backed rebel groups, on and off, such as the Kurd-led Syrian Democratic Forces. Last week Trump indicated he wanted to pull out entirely – even though Isis remains undefeated.

Facebook Twitter Pinterest ‘Allied military intervention, better late than never, is necessary to avoid future atrocities.’ Illustration: Andrzej Krauze

For Obama, Syria was a blot on his record, in the same way Rwanda besmirched Bill Clinton’s legacy. For present-day western leaders, including Trump, Theresa May and France’s Emmanuel Macron, stopping the Syrian carnage is a moral imperative they can no longer ignore. Eastern Ghouta has become a Syrian Srebrenica. It is our shared shame.

If morality is not enough, then consider self-interest. What difference is there, really, between unleashing chemical weapons on the streets of Douma and the streets of Salisbury? May has been at pains to stress the measures taken against Russia are about more than the unfortunate Skripals. They are about ubiquitous, ongoing, egregious Russian wrongdoing, she says. Well, Syria is a prime example of malign Russian meddling.

France and Britain should use the international solidarity forged in Salisbury’s wake to intensify pressure on Vladimir Putin over Syria. Paris and London should also join forces to ensure that before he shoots off his mouth and missiles again, Trump and his new pet hawk, John Bolton, closely coordinate any US military action in return for Anglo-French participation and support.

Concerted and sustained joint military intervention does not mean ground troops. It does not mean invasion and occupation. It does not mean nation-building or crass cultural colonisation. It means destroying Assad’s combat planes, bombers, helicopters and ground facilities from the air. It means challenging Assad’s and Russia’s control of Syrian airspace. It means taking out Iranian military bases and batteries in Syria if they are used to prosecute the war. And it means keeping up the pressure when they push back, which they will, until Putin, his Damascene partner-in-war-crimes, and Iran’s cocky Revolutionary Guard commanders get the message, feel the pain, count the escalating cost, and stop trying to kill civilians – in Douma, Salisbury, or anywhere else.

Only Assad’s victory will end Syria’s civil war. The west can do nothing | Simon Jenkins Read more

Military action would also tell Israel that it is not alone – and does not have a free hand. Its opportunistic overnight bombing raid was not about avenging Douma. It was another warm-up act in what many predict is a coming war with Iran, Syria and Lebanon’s Hezbollah. Nipping such a region-wide conflict in the bud is another good reason to step in decisively now.

It is just not good enough to say there is nothing the west can do in the face of mass murder. Are we straw men? Can we no longer distinguish between right and wrong? Allied military intervention, better late than never, is necessary to avoid future atrocities, spare innocent lives – and neutralise the vicious poison that everywhere is corroding faith in the universal rights of man, the international order, and international law.