The Washington Post said three basic options have emerged in a strategy review by Joint Staff, but the one gaining favour among the military is a hybrid that would beef up US forces for a short period to tamp down sectarian violence.
Pentagon spokesman Bryan Whitman would not comment specifically on the story, but said it would be "premature" to second-guess the outcome of a series of strategy reviews now underway in Washington.
"The fact of the matter is the United States military does have the ability to put more forces on the ground if we need to put more forces on the ground," he said.
"We've always said the size of the US presence as well as the coalition presence will be based on conditions on the ground and by the recommendations of the commanders in the field," he said.
General John Abizaid, the US commander in Iraq, said last week that a 20,000-troop increase in the 144,000-member US force would have a temporary effect on the violence.
But he said the pool of available combat troops in the US Army and the Marine Corps was not large enough to sustain such an increase.
Abizaid said more troops were not needed at the moment, but he warned that a withdrawal of US troops would lead to an increase in the level of sectarian violence wracking the country.
A sizeable boost in US troops would run against a strong current of public anger over Iraq which swept Democrats to power Congress in November 7 mid-term elections.
"Politically this is the worst possible time to be proposing an increase in the force level because the public has just voted to reduce the US involvement in the country," said Loren Thompson, an analyst at the Lexington Institute.
"I think that politically the easiest option to execute is a gradual redeployment to Kuwait, which would leave a core of perhaps 80,000 forces in country but remove many of the non-essential personnel from the line of fire," he said.
The Post, which cited unidentified senior defence officials, said the secret Joint Staff review offers three basic options -- "Go Big," "Go Long" and "Go Home."
The "Go Big" option calls for a classic counter-insurgency operation that would involve several hundred thousand additional US troops as well as heavily armed Iraqi police, the newspaper said.
That option has been all but rejected by the study group, which concluded that there are not enough troops in the US military and too few effective Iraqi forces, The Post said.
The "Go Home" option was rejected by the Pentagon group as likely to push Iraq directly into a full-blown civil war, according to the report. The "Go Long" option calls for shrinking the US force in Iraq, replacing the current combat force with an extensive program of military training and advising of the Iraqi security forces that would last for years, it said.
The Post said the military is leaning toward a combination of "Go Long" and "Go Big," surging US force levels by 20,000 to 30,000 troops for a short period while the training program is being expanded.
Once the transition has been made, US force levels in Iraq would drop to about 60,000, according to the Post.
The temporary increase in force levels is intended to signal to Iraqis that the shift in posture is not a disguised form of withdrawal, the Post said.
The military would come up with the extra troops by extending tours of some units, bringing in others ahead of schedule, and activating some Army reserve units, it said.
Senator Joseph Biden, who is expected to be the new chairman of the Senate Foreign Relations Committee when Democrats take over the chamber next year, said on Monday he favoured a variation of the "Go Home" pullout option.
"Of those three, the last one would be the better one," though still not ideal, Biden said, speaking on the NBC Today Show.
"The best one is to, in fact, begin to let the Iraqi leadership know we're not going to be staying," Biden said.
"Over the next four months, let them know we're going to start to phase out, force them to have to address the central issue," which he said is "how to get Iraqis to stand together."
Biden added that the administration also needs to make more diplomatic outreach to "get international consensus that will embrace whatever agreement they make internally."

Copyright AFP (Agence France-Presse), 2006