Israel and Iran are walking us towards the precipice in Syria

Concerted effort to constrain both powers is needed before the crisis becomes uncontainable

These pages have repeatedly warned that the conflict in Syria, if not resolved, would escalate into an uncontainable war with global implications. That moment may have arrived on Thursday, when Israel launched a series of missile strikes against Iranian military installations in Syria. Some 70 Israeli missiles rained down on Syria in the overnight attack, killing 23 Syrian regime and allied fighters. An Israeli airstrike south of Damascus killed more than two dozen people. Israel claims the attacks were in retaliation for Iranian rockets fired at Israeli military positions in the Golan Heights, a territory that has been under illegal Israeli occupation for more than four decades. The UN Secretary General, Antonio Gutteres, urged world leaders on Thursday, as he marked anniversary of the end of the Second World War in Europe in 1945, to "pledge to be ever-vigilant so that we do not sleepwalk our way into war".

In Syria, no party can invoke somnambulism as an alibi. What has happened – and continues to happen – there is the result of conscious choices by all involved. Iran, in its ruinous pursuit of hegemony, sought to build in Syria a military beachhead under the cloak of the conflict. It seconded advisers to Bashar Al Assad's regime, shipped fighters to kill on his behalf, and transferred heavy weapons and other equipment wildly disproportionate to its stated goal. Israel, a serial violator of international laws, frequently breached Syria's sovereignty to stage pre-emptive attacks. The irreparably fractured landscape of Syria is congested with the forces of Russia, Hezbollah and Nato allies Turkey and the United States, each advancing its own agenda. Emboldened by its perceived successes in Syria, and enriched by the nuclear deal, Iran began engaging in deadly brinkmanship, pushing to see how much it could get away with. Thus its missiles, supplied to the Houthi militias in Yemen, have been fired at Saudi Arabia. Its agents, especially Hezbollah in Lebanon, have spread its terror far and wide in the region.

European leaders have called for restraint, with German Chancellor Angela Mekel emphasising that Syria is now a matter of "war and peace". Yet words are not enough. Reports are already emerging of an Iranian plan to retaliate. Immediate concerted international action is essential to constrain both Israel and Iran. European leaders who are still intent on preserving the nuclear deal must tell Tehran that its reign of terror must end. Israel, rather than being mollycoddled, must be held to account for its brazen use of force before it plunges the world into a mutually destructive war. The events of Thursday are the direct result of the failure to bring the Syrian civil war to an end. We cannot afford to let the conflict fester any longer.