WASHINGTON - A new National Intelligence Estimate paints a grim view of the violence and political situation facing the United States in Iraq, according to officials familiar with a much-anticipated, collaborative analysis from all 16 U.S. spy agencies.

The Office of the National Intelligence Director was releasing an unclassified summary of the document - entitled "Prospects for Iraq's Stability: A Challenging Road Ahead" - on Friday. President Bush was briefed on its conclusions on Thursday.

The newest intelligence assessment concludes that success there depends on improving poor security, which is fueling sectarian violence, hurting the government and slowing reconstruction. Officials who spoke on condition of anonymity because the document had not yet been released said that the document is a rigorous, grave assessment of the situation facing Iraq, but it does reveal areas where change could lead to positive developments.

The report addressed security threats in Iraq posed by both Iran and Syria.

The general conclusion was that the biggest security problem is of a sectarian nature but that outside Iranian involvement makes the situation worse. Similarly, it said that Syria's failure to control its borders has allowed foreign jihadists to enter Iraq.

The administration said the document provided clear and compelling evidence of why the U.S. strategy in Iraq had to be changed. Bush, in a policy reversal, announced on Jan. 10 that he was sending an additional 21,500 U.S. troops to Iraq.

The report warned of ominous consequences if the violence was left unchecked. "Unless efforts to reverse these conditions show measurable progress during the term of this estimate in the coming 12 to 18 months, we assess that the overall security situation will continue to deteriorate," the report said.

The Bush White House saw the document as support for the president's new strategy and troop buildup. "Coalition capabilities including force levels, resources and operations remain an essential stabilizing element in Iraq," the report said.

It argues against a rapid withdrawal of U.S. troops, according to an administration official familiar with the conclusions. Such a move would fracture the Iraqi army, lead to the creation of an al-Qaida state in Anbar Province and result in significantly increased violence, the report said.

It drew no conclusions about whether Iraq has fallen into a civil war, said an official, insisting on anonymity because the document has not been released.

The Washington Post reported Friday that the estimate describes an increasingly perilous situation in which the U.S. has little control and further deterioration is possible. According to the paper, the report says that al-Qaida activities remain a problem, but Iraqi-on-Iraqi violence is the primary source of conflict and the most immediate threat to U.S. goals.

National Intelligence Director John Negroponte, who briefed Bush Thursday morning, told the Senate Foreign Relations Committee earlier this week that Iraq was "at a precarious juncture."

"That means the situation could deteriorate, but there are prospects for increasing stability," said Negroponte, who is stepping down as the nation's top intelligence official to join the State Department as its No. 2 official. However, he cautioned that stability depended on bringing an end to sectarian violence and fighting all extremist elements.

Congressional officials have been pressing Negroponte for a completed estimate since before the November elections. It comes as Congress is considering resolutions about Bush's decision to send thousands of additional troops into Iraq as part of an overhaul to his war policy. He has also said the United States will put more pressure on the Iraqis to repair the security situation.

The administration's decision to release the National Intelligence Estimate marks a new way of doing business at the National Intelligence Council.

The 12 to 15 high-level estimates that it produces annually contain the best thinking from the nation's 16 spy agencies. But these typically classified reports have been leaked recently, to the frustration of administration officials.

In a brief overview of the assessment last month, Thomas Fingar, who heads the National Intelligence Council, has said recently that it will be difficult - but not impossible - for Iraqi Prime Minister Nouri al-Maliki to succeed.

"The logic that we have applied looks at the importance of security - security as an impediment to reconciliation, as an impediment to good governance, as an impediment to reconstruction," Fingar testified before the Senate Intelligence Committee.

Fingar said that improved stability "could open a window for gains in reconciliation" among Iraq's sectarian groups, including the Sunnis and the Shiites. And that "could open possibilities for a moderate coalition in the legislature that could commit better governance," he added, acknowledging the assessment was full of conditional statements.

Fingar said the government's analysts believe that al-Maliki "does not wish to preside over the disintegration of Iraq."

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