A US led invasion of Iraq looks almost certain. President George Bush and his advisors have committed themselves to regime change in Baghdad too often and too publicly to risk the political humiliation of last minute diplomatic compromise. By early next year American and British troops, with or without a UN mandate, will be advancing on Iraq’s capital from their bases in Kuwait and Turkey. But the forces ranged against them should not be underestimated. This is unlikely to be quick, easy or without pain.