Yesterday's nightmare of violence in Baghdad returned the city to the worst days of 2006, before the extra surge of United States troops designed to provide the city with extra security. The death of up to 200 people in a string of suicide car bombings mocked the announcement earlier yesterday by the Iraqi prime minister that the gradual handover of security in the country's provinces by US and British forces is going according to plan.
This was more than a bad day in their struggle for greater security in the city. Their mission is failing and there is precious little evidence that they and the weak Iraqi government can find the military and political will to reverse the trend.
Yesterday's deaths come hard on the heels of wider security and political setbacks. Last week bombers penetrated Baghdad's Green Zone containing the government compound and administrative apparatus. They destroyed one of the main bridges across the Euphrates, making it even more difficult for Baghdadis to cross the city. On Monday the main Shia party withdrew from prime minister al-Maliki's coalition, rendering it virtually non-functional.
Led by Moqtada al-Sadr, the decision is to demand a timetable for withdrawing foreign troops from Iraq. He has been in Iran for several months to avoid becoming a political target of reasserted US power in Iraq. His party base has a formidable capacity to subvert that power; but it has been neutralised in security terms by his decision to forbid guerrilla actions or suicide bombings from his supporters, even if provoked by US troops. This latest power play does not threaten another military front, but it reinforces demands within and without Iraq for a withdrawal timetable to be agreed.
Until this is done an increasingly dangerous political and security vacuum will open up in Iraq. Pressure is mounting politically to fill it in US and British politics, where demands for a withdrawal timetable make more and more political sense. The established parties in Iraq resist the idea and so does President Bush and his administration, who cling to the idea of winning this war. That is not possible. A withdrawal timetable would make it easier for agreement to be reached in Iraq on a new government, who should be involved in it and how the new political regime there should be organised.
Decisions on how to share power between Shias, Kurds and Sunnis and how to distribute the country's oil resources between the centre and its new regions cannot be made until the current security impasse is resolved. Those responsible for yesterday's horrifying violence presumably aim to force the pace by maximising chaos and destruction. It is Iraq's misfortune that this grim quagmire of violence seems to make political sense.
President Bush's "surge" has less and less justification, without a realistic strategy for withdrawal from Iraq. Military and political decisions are being forced together once again to determine its future.