The umbrella insurgent group Islamic State of Iraq has claimed responsibility for Thursday's attack in the Iraqi Parliament cafeteria which left one lawmaker dead and 22 people wounded.
The Associated Press reports that the group, which includes Al Qaeda in Iraq, posted the claim on a website frequently used by insurgents.
The Islamic State said in Internet postings that it had delayed claiming responsibility to allow its men to flee from investigators who have been rounding up and questioning parliament employees.
"A knight from the state of Islam ... reached the heart of the Green Zone ... the temporary headquarters of the mice of the infidel parliament and blew himself up among a gathering of the infidel masters," the Islamic State said in the statement posted on one Islamist Web site commonly used by insurgents.
The Site Institute, which tracks militant postings, said the claim by the Islamic State appeared authentic.
The suicide bombing took place in the Iraqi Parliament, inside Baghdad's heavily fortified Green Zone, which houses the Iraqi government and US headquarters in the region. The US military reported Thursday that eight people were killed in the attack, but revised the death toll downward on Friday.
Reuters reports that despite the attack on Iraq's government center, "scores" of parliamentarians attended sessions on Friday, normally a day of rest for Muslims, in a show of unity against the terrorist attack and to remember Mohammed Awdh, a member of the Sunni National Front for Iraqi Dialogue, who was killed in the bombing.
"Whether we are in or out of the government and the political process, we have to find a solution to national reconciliation," Shi'ite Vice President Adel Abdul-Mahdi, who survived an assassination attempt in February, told parliament.
Previous calls for unity by Iraq's leaders have mostly fallen on deaf ears as sectarian violence has spiralled.
"This is undeniably a difficult blow, but it should unify us to confront the evil of terrorism and it proves that terrorism is indiscriminate -- Sunnis, Shi'ites, Kurds and Arabs were maimed in this attack," Deputy Prime Minister Barham Saleh, a Kurd, told Reuters, a message he repeated in parliament.
Despite the parliamentarians' display of resolve, the bombing could prove damaging to the Iraqi government's efforts to deal with the political problems they face. In an analysis for the AP, Steven Hurst writes that the attack is "certain to only harden positions" in parliament, which could make compromise "nearly impossible," which in turn may derail passage of fiercely debated laws, such as the law to divide Iraq's oil income.
Rajiv Chandrasekaran, author of "Imperial Life in the Emerald City: Inside Iraq's Green Zone," expressed to the BBC similar concerns about the bombing's effect on Iraq's political progress.
"The current Bush administration security plan for Baghdad, this troop surge, is based upon this notion that if you create pockets of security in Baghdad, political leaders will come together to make the necessary compromises to move forward on important pieces of legislation aimed at national reconciliation," Mr Chandrasekaran said.
"But if your parliament has been blown up, if legislators don't feel secure coming to work, it's hard to see how you can move forward with those very important political reconciliation initiatives."
The Guardian reports that US officials acknowledged that even the Green Zone is not immune from the attacks that plague Iraq's capital.
"The international zone is not safe, it is just safer than the rest of the city," said Lieutenant Colonel Christopher Garver. "Enemies of the country are trying to drive a wedge between the people and the government." In Washington the secretary of state, Condoleezza Rice, said: "We know that there is a security problem in Baghdad. This [crackdown] is still early in the process and I don't think anyone expected that there wouldn't be counter-efforts by terrorists to undermine the security presence."
Reuters, citing "a senior government source," writes that there may have been warning the building was a target.
"We had prior intelligence that there would be an attack on the parliament," the source told Reuters, without specifying when or how the information had been received. ...
"It seems initial, initial evidence points to the possibility a member of a security detail of a Sunni member of parliament might have been involved. That is based on talks with survivors and some of the wounded," the source said.
Reuters notes that security had been tightened at the building Thursday, with bomb-sniffing dogs patrolling earlier in the day.
Still, an attack on the Green Zone was far from unexpected. The Washington Times writes that Brian Marshall, a former State Department employee who worked in the US embassy in Baghdad, said, "We were getting periodic reports about threats to the Green Zone, so there were a lot of indications that an attack could take place." And The Washington Post reports that some experts suggest that "the only surprise [about the bombing] was that an attack inside a major government installation had not happened more often."
"This is bad news, but they've been trying to secure a large area in the middle of a war zone, and the fact is that it has so far happened rarely," said Michael E. O'Hanlon of the Brookings Institution. "The Green Zone is still the least of our concerns."