There is a mega-bomb waiting to explode in the Middle East. Biden must not light the fuse by attacking Iran | Simon Tisdall

The US president is under immense pressure to hit back at Iranian-backed militias, but that would be a disaster

The unprecedented Hamas terrorist attacks on Israel on 7 October set a fuse burning under the entire Middle East. Now the fearsome, figurative mega-bomb to which that fuse is ultimately attached - direct conflict between the US and Iran - may be about to explode, with devastating consequences.

With every day that Israel's illegal bombardment of Gaza continues, with every new estimate of the tens of thousands of Palestinian dead, a huge detonation edges closer. From the Red Sea to Iraq, Syria and Lebanon, an escalating, four-month spiral of violence, principally involving pro-Palestinian, Iran-backed militias, has been inexorably building.

Simon Tisdall is a foreign affairs commentator. He has been a foreign leader writer, foreign editor and US editor for the Guardian