Sectarian attacks and reprisal killings that began with the bombing of a revered Shia mosque are troubling but do not necessarily portend further violence, James F Jeffrey, senior adviser to Condoleezza Rice, the US secretary of state, said in an Associated Press interview.
"It indicates that the path to national reconciliation and the path to a national compact that we're striving so much for has a way to go. It means we better continue working and work harder on it," Jeffrey said.
Jeffrey discounted the threat of all-out civil war but warned that the volatile situation could worsen. "There is still the risk of sectarian attacks" double or triple the scale of what Iraq witnessed before the 22 February mosque bombing in Samarra, he said.
"If they were to grow worse, then I think we would have a different situation."
In a briefing from Baghdad to reporters at the Pentagon, General George Casey said: "Now, it appears that the crisis has passed."
Casey, the top US military commander in Iraq, added: "We all should be clear: Iraqis remain under threat of terrorist attack by those who will stop at nothing to undermine the formation of the constitutionally elected government."
Along with the increased level of violence, the scale of targets on Sunni mosques was new, Jeffrey said.
"We were very careful neither to overplay this nor to indicate that this is just business as usual," he said.
US officials have discounted the
possibility of civil war for now
"This was a blow to the efforts to bring together the various political forces, but it also illustrates the need for them to come together as soon as possible and that's where we are focusing our efforts."
An extraordinary daytime curfew and vehicle restrictions helped to curb the worst of the sectarian killing, but attacks continued this week.
Casey said US military officials believed that about 350 civilians overall had been killed in the violence, though some Iraqi officials had used higher figures.
Thursday's attacks claimed 58 lives. "I think it's safe to say that a major attack, particularly on a religious site, would have a significant impact on the situation here coming in the next couple of days," Casey said.
Jeffrey has said that al-Qaida leader Abu Musab al-Zarqawi is the "likely suspect" in the 22 February mosque bombing, although he said he had no clear evidence of that.
No Iran link
Jeffrey added that although neighbouring Iran was trying to increase its political pull among Iraq's factions, "we see no specific line that leads you directly to Iran in any of what happened in the last week and a half".
Casey said officials did not know who was behind the bombing, but suspicions were focusing on al-Qaida or groups linked to it "because it meets the type of event that they have been saying that they were going to do here".
Sunni fighters remain locked in
battle with Iraqi security forces
Zalmay Khalilzad, the US ambassador in Baghdad, has been a key back-room dealmaker in government talks, but Jeffrey said the US was not playing favourites among candidates for prime minister or other posts.
He would not grade the performance of Ibrahim al-Jaafari, the interim prime minister, but did not sound enthusiastic about the prospect that the Shia politician may serve another term.
Sunni Arabs; the Kurds, who are mainly Sunni; and secular political leaders have mounted a campaign to deny al-Jaafari the job.