Just when you thought that Iraq was the sideshow and Afghanistan the main event, the far-too-familiar sound of sirens screeching and the bereaved wailing in the streets of Baghdad remind you otherwise. A government spokesman, Ali al Dabbagh, immediately pointed the finger of blame at al Qa'eda militants or members of Saddam Hussein's former government, and demanded a UN investigation. Nevertheless, it was too early to know exactly who carried out the bombing, which killed more than 130 people.
What is more certain is the character of the bombers. They were sinister and cynical enough to know that the best way to embarrass the government of Nouri al Maliki was to prove it incapable of preserving what most Iraqi's yearn for - security - and show it unable to put to rest worries about what they most fear - a return to the bad old days of 2006, when Iraq was on brink of all-out sectarian war.
After the bombing, comparisons were immediately drawn to the blasts in August that killed 100 in Baghdad. The targets then were the ministries of finance and foreign affairs; this time, it was the ministry of justice and a provincial government office near the Green Zone. In the run-up to parliamentary elections in January, when Mr al Maliki, the prime minister, is expected to seek re-election, both bombings serve to push the government careering towards the third rail of Iraqi politics: it can neither ensure security nor can it ease US troops off Iraqi territory.
Since most US troops withdrew from Iraq's cities in June, violence has been on the rise. No one is saying it is the leading edge of a gathering storm that threatens to reach the proportions of 2006. Yet the trend is worrying. Yesterday's bombing did not occur on the edges of Sadr City; it happened near the heart of what is supposed to be the safest and most secure section of the Iraqi capital. Yesterday's attack inevitably raises the question: how fragile is Iraq? Although US and Iraqi officials privately acknowledge that it is neither as secure as advertised nor as brittle as feared, truth be told, nobody really knows. The definitive answer awaits the withdrawal of all US combat troops, scheduled for the end of 2011.What remains until then is a gnawingly ambiguous situation, summed up in August by Anas al Tikriti, a Sunni Islamist: "Iraq today is halfway between either being on the verge of collapse or on the verge of salvation."
For now, the most pressing question is whether yesterday's events will refocus minds in Washington and slow the Obama administration's shift of money, attention and personnel to Afghanistan and its volatile frontier with Pakistan. The United States has 130,000 troops in Iraq, almost twice the number it has in Afghanistan. The US troop count is due to drop quickly to about 50,000 by this time next year, though Washington deftly avoids indicating how many "advisers' will remain in Iraq.
Nevertheless, this US administration, like its predecessors, subscribes to the view that the attention span of the public is short and narrow, and cannot handle two trouble spots - let alone three, if you include Iran - at once. Last month, the senior US commander in Iraq, Gen Ray Odierno, said this shift of attention worried him. He warned that there was always a risk that the security situation in Iraq could deteriorate.
"We have spent a lot of money here," Gen Odierno said in Baghdad. "We've spent a lot of lives here, both the US and the UK. So we have an opportunity. It's important to see this through." Gen Odierno suggested that lingering insurgencies of the kind that could have authored yesterday's bombing were not Iraq's main source of insecurity. "The endemic corruption within the Iraqi system - not only the security forces, but the system - is still probably the biggest problem facing Iraq," he told the BBC.
With elections and the prospect of more bombings looming, it is worth recalling that aside from the gauzy recollections of some Iraqis, there has never been a golden age of Iraqi politics when Shias and Sunnis, Arabs and Kurds, or Muslims and Christians coexisted in one big happy Iraqi family. Saddam Hussein, in particular, saw to that. For now and the immediate future, ties of ethnicity, religion and clan will remain the determining factors in Iraqi politics - and the source of peril for anyone who wants to exploit them, as they demonstrated so hideously yesterday.