General David Petraeus, the top US commander in Iraq, has started assessing military options for the country after the troop surge winds down next summer as a debate intensifies in the Pentagon over what to do next.
President George W. Bush approved the surge, an increase of five combat brigades, or 30,000 troops, this year to try to reverse spiralling violence in Iraq. General Petraeus and Admiral William Fallon, head of US central command, are set to make recommendations about future options to Mr Bush in March.
At the heart of the debate in the Pentagon is whether the US should continue to withdraw troops after the surge has wound down - thereby relieving pressure on the heavily stretched army - or whether to keep a post-surge force of about 130,000 troops for some time to bolster the security gains.
"General George Casey, the army chief of staff who preceded Gen Petraeus in Iraq, has repeatedly warned that the US is deploying in Iraq at an unsustainable pace."
In recent months the US military and Iraqi security forces have overseen significant improvements in security as violence against coalition forces and Iraqi citizens has declined sharply.
In September Gen Pet-raeus told Congress the surge would be reversed by next summer, leaving 15 combat brigades and support forces in place. After this, Robert Gates, the US defence secretary, said, he hoped Gen Petraeus would be able to recommend in March reducing US forces to 100,000, or 10 combat brigades, by the end of 2008 - a view understood to be shared by the joint chiefs of staff.
In an interview with the FT, Adm Fallon said it was prudent for the US to prepare a range of plans, since it was difficult to predict now how security would look at the end of next summer. He had "high confidence" that coalition forces would be successful, adding a "phased handover" would help Iraqi security forces gain confidence. "We have a lot of factors at play here, not least of which is to have the Iraqis have the determining hand on their future."
Some senior US military figures in Iraq, including Lt Gen Raymond Odierno, day-to-day commander of operations, argue the US should not jeopardise the security gains by rushing to make further troop reductions.
Several military experts familiar with the debate on troop levels said Gen Pet-raeus was likely to favour maintaining a post-surge force of close to 15 brigades in place after the summer.
"Our field commanders will want to evaluate and assess for a number of months after the reduction is complete in July before any further (troop cuts) are considered," said Jack Keane, a retired general who has advised the White House on the surge policy.
"Others would desire to continue the reductions without a pause for an assessment. This is far too much risk to the significant gains that have been made."
Gordon Johndroe, national security council spokesman, said Mr Bush would receive advice from a variety of sources, but "decisions will be based on conditions on the ground and what is necessary to maintain the security gains that have been made over the last few months".
Toby Dodge, an Iraq specialist at Queen Mary University London, said Gen Petraeus would face "a great deal of pressure" to withdraw troops as quickly as possible. But Michael O'Hanlon, a military expert at the Brookings Institution, said the Pentagon would probably conclude the US needed to keep closer to 15 combat brigades in Iraq.
"Common sense would say that you would to get some feel for how this is working before you commit to . . . lower force levels than we have at any time since we have been there, which is what the 10-brigade goal would represent," he said.
