The bomb that exploded in the cafeteria of the Iraqi parliament on Thursday has shaken the inner corridors of power in the country, and caused alarm in Washington, whose diplomats and officials often visit the building that was hit.
By Jim Muir
BBC News, Baghdad
It has also prompted an investigation into how the suicide bomber could have got through the elaborate security measures in place around the building and the adjacent Green Zone.
Even by current Iraqi standards, it was an extraordinary day.
Imagine waking up in London, to the news that Hammersmith Bridge had just been blown away by a lorry full of explosives.
And then at lunchtime, a bomb in the cafeteria at parliament - more than anything else, the explosion at the Iraqi parliament resonated around the world.
The sad fact is that, had this bomb not gone off in parliament and killed some MPs, it would barely have been reported internationally
This was the inner sanctum, the seat of power, the very heart of the regime set in place by the Americans and their allies, and heavily protected by them.
If even this could be breached by the bombers, where in Iraq was safe?
The vivid television footage captured by a local station that happened to be interviewing an MP when the bomb went off, further magnified the impact, and gave a taste of the horrific scenes that follow every single bombing of this kind that happen in Iraq on a daily basis.
In fact this one probably caused more alarm in Washington than it did among the people of Baghdad.
The sad fact is that, had this bomb not gone off in parliament and killed MPs, it would barely have been reported internationally in a country where such outrages often claim scores of lives, in crowded streets and markets and mosques.
Ordinary Iraqis will be more affected by the destruction of a key bridge
That is why many Iraqis reacted with indifference to the bomb in parliament.
"What have they ever done for us?" was the answer of one when he heard the news. "What I care about are all the ordinary people who get blown to pieces every day."
Apart from those who live in the isolated bubble of security that the Green Zone normally is, most of Baghdad's residents would be much more affected by the destruction, just a few hours earlier, of the Sarrafiya bridge, one of the major links across the Tigris between the city's two halves.
But the attack on parliament may have focused American and other minds on the failure so far of the much-trumpeted security "surge" in Baghdad, to affect one half of the violence that's tearing the country apart.
Since it began over two months ago, the security plan has considerably reduced the level of sectarian abductions and killings.
Many of them were attributed to the Shia militias, which have melted away in deference to the plan.
But the other half of the violent equation, the deadly bombings by Sunni insurgents, usually aimed at Shias in one way or another, has continued unabated and even been stepped up.
The Shia militias are already openly asking why the security plan is so unbalanced.
And ordinary Iraqis are asking why they're still being massacred in their scores and hundreds by these massive bombs virtually every day, somewhere in the country.
Perhaps the explosion in parliament will spur the planners to redouble their efforts to stop the bombers slipping through the net, not just in the Green Zone, but elsewhere too.
But it has also given those at the centre of power here in Baghdad a taste of what may lie ahead, if the security plan ends up failing.