The drumbeat of conflict between the US and Iran has become suddenly deafening. The killing of Iran’s top security and intelligence commander in a US air strike on Baghdad airport is a startling escalation of the stand-off in the region. Tehran will see it not just as a military body blow but tantamount to a declaration of war. America’s allies are disconcerted. Every move on the Middle East chessboard will now carry with it the serious risk of triggering a broader conflagration.

The pretext for the US strike was relatively clear. Washington had blamed an Iranian-backed militia in Iraq for firing rockets at US troops that killed an American civilian contractor. In the cycle of regional attacks and counter-attack, killing a US national was always seen as a red line. President Donald Trump responded by ordering five air strikes on the militia — which in turn triggered a siege of the US embassy in Baghdad. For Washington, the echoes of the seizure of America’s embassy in Tehran after the 1979 Islamic revolution were more than uncomfortable.

In military terms, moreover, the elimination of the head of the Iranian Revolutionary Guards’ external forces is a significant prize for the US — bigger in some ways than the 2011 killing of Osama bin Laden. As commander of the elite Quds Force, Soleimani was the powerbroker and puppet master orchestrating proxy forces through which Iran projected its influence across the Middle East. His popularity at home, with signs that he was being groomed for high office, makes assassinating him — in a third country — especially provocative and high-risk.