By Paul Reynolds
World affairs correspondent, BBC News website
It is a key week for US policy in Iraq.
General Petraeus and President Bush: Key week ahead
The top US commander in Iraq, General David Petraeus, will give evidence in person to Congress.
President George W Bush will later file a formal report on the performance of the Iraqi government in meeting US-set benchmarks for political reconciliation.
The most likely outcome of this intense period of assessment is that the current military strategy will continue for the moment - with the hope of a relatively small reduction in troop levels early next year and another assessment in six months' time.
The Iraqi government will also come under renewed US pressure to do more to encourage political progress.
To adapt a nautical phrase, it will be "unsteady as she goes" - ie the course is a difficult one in rough seas, but no alternative is reckoned to be available at the moment.
Petraeus before Congress
General Petraeus is expected to hold out just enough hope to enable the Bush administration to see off efforts by Democrats in Congress to set a timetable for a withdrawal. He aims to buy time for the current strategy.
Starting on Monday, he will argue before congressional committees that the "surge" of US forces into Iraq this year (raising the level by 30,000 to more than 160,000), coupled with a new strategy of holding ground and seeking local allies, has won some "momentum", as he put it in a letter to his troops.
By April, decisions will have to be taken on whether to reduce number to the pre-surge levels because of the strain on army resources. Reductions will be the subject of further intense debate
He has admitted, however, that success has been "uneven".
He will highlight the improved security picture in the western province of Anbar, where tribal leaders have made an alliance with US forces against al-Qaeda fighters.
Relying on traditional leadership might not represent the kind of democratic change that the US wanted to see in Iraq, but any help is gratefully received in present circumstances.
However, progress is relative. A vivid account by Michael Gordon in the New York Times about how US forces are linking up with the tribal leaders also indicated how dangerous the area still is - Gordon was nearly blown up in a sophisticated ambush and the US colonel guiding him was wounded.
And according to Yahia Said of the London School of Economics, tribal loyalties are not reliable.
"They can turn on a dime. These same people were swearing their undying loyalty to Saddam Hussein," he commented.
Timetable for 2008
General Petraeus is nevertheless holding out the prospect of withdrawing perhaps a brigade of about 4,000 troops in the new year. That would be more symbolic than anything - a gesture towards Congress and a reminder to the Iraqi government that US support has its limits.
By April, decisions will have to be taken on whether to reduce number to the pre-surge levels because of the strain on army resources. Reductions will be the subject of further intense debate.
If Congress is not satisfied, future funding for the war could be in doubt and pressure would grow for a withdrawal
The US commander will probably want to keep as many troops for as long as possible. After all, he was the author not only of this plan but also of the US army's manual of counter-insurgency. One of the key principles enshrined there is this: "Counter-insurgents should prepare for a long-term commitment."
His plan envisages establishing security in Baghdad and other key areas by the summer of 2008 and nationwide by the summer of 2009.
In his letter, he compared the position to that of a team in an American football game: "We are, in short, a long way from the goal line, but we do have the ball and we are driving down the field."
However he and the US ambassador to Iraq, Ryan Crocker, will also express disappointment at the pace of political progress in Iraq. The hope had been that the reinforcements would reduce violence sufficiently to enable the Iraq government to fulfil a list of 18 benchmarks aimed at political reconciliation.
General Petraeus said in his letter: "It has not worked out as we had hoped."
Framework for decisions
The congressional hearings are part of an elaborate structure of assessment laid down by Congress in legislation in May that gave extra funding for the wars in Iraq and Afghanistan.
This legislation stated: "The United States strategy in Iraq, hereafter, shall
be conditioned on the Iraqi government meeting benchmarks... "
The most important of the 18 benchmarks include the implementation of legislation on reforming laws against the employment of former Baath party members and on oil revenue sharing.
These benchmarks are not formally linked to troop numbers. But if Congress is not satisfied, future funding for the war could be in doubt and pressure would grow for a withdrawal. So they matter.
President Bush was required to report twice on whether the Iraqis were meeting the marks. The first report in July gave a mixed picture. His second report is due this week, possibly on Wednesday.
In advance of that report, General Petraeus and Ambassador Crocker were ordered to make themselves available to give evidence before Congress.
In addition, Congress' investigative arm, the Government Accountability Office, was told to draw up its own assessment of benchmark compliance. It issued a critical report last week.
Congress also ordered a professional assessment of Iraq's military and police. It was led by retired General James Jones and said in its report last week that the Iraqi police were "incapable" and that the (improved) Iraqi army could not operate independently for another 12-18 months.
The assessments will culminate in a television address by President Bush, possibly on Thursday.