WASHINGTON: A new burst of violence in Iraq sharpens the differences among US military leaders over how to balance the risk of pulling US troops out too quickly and the danger of waiting too long.

At stake are the chances for success in Iraq as well as the long-term health of the US military.Navy Adm Mike Mullen, chairman of the Joint Chiefs of Staff, said he is not convinced that attacks like Friday’s twin suicide bombings in Baghdad require the Pentagon to pause or freeze the reduction in forces after the number of combat brigades shrinks to 15 at the end of July.

“I don’t see that at this particular point,” Mullen told a Pentagon news conference hours after the attacks. He stressed that he and the service chiefs still are studying the matter of troop withdrawals beyond July.

Too rapid a withdrawal could lead to an unraveling of the security improvements of recent months, a risk that President George Bush said this week he would not take. Yet keeping troops there longer than necessary could push the already stressed Army and Marines to the breaking point.

In Baghdad, two mentally disabled women strapped with remote-controlled explosives, and possibly used as unwitting suicide bombers, brought carnage to two pet bazaars, killing dozens in the deadliest day in the capital since Bush sent an additional five Army brigades to Iraq last spring.The debate in the Pentagon is over what to do when those five brigades are brought home in coming months. It is complicated by the mixed picture in Iraq, where violence levels are far lower than a year ago but have shown signs of worsening in recent days, especially in volatile areas north of Baghdad.

Defence Secretary Robert Gates has said he hopes conditions in Iraq allow a cutback to 10 brigades by year’s end. That would allow the Army to reduce combat tours from 15 months to 12 months.

By contrast, senior commanders in Iraq, led by General David Petraeus, have made it known they would like to have a pause at midyear for a “period of assessment,” perhaps into the autumn months, before making a recommendation to Bush on when and at what pace to resume the withdrawal of US forces. Thus, they would keep the force at 15 brigades for some period well beyond July.

Their concern is that July will be too soon to reliably judge whether the current round of troop drawdowns, totaling at least 21,500 troops, resulted in deterioration of security and stability.

The most senior US commander in Iraq below Petraeus, Army Lt General Ray Odierno, said on Friday that he favours a “deliberate, considered” course of action on troop withdrawals that is in line with the results of an assessment after July.

Bush’s top diplomat in Baghdad, Ryan Crocker, said on that he and Petraeus plan to report to Congress in April about how to proceed with troop levels and strategy. He would not say whether he thinks a redeployment pause will be needed.

“It’s not simply assessing what conditions are with respect to the status of Iraqi security forces, sectarian tensions, level of violence as they are currently,” Crocker said. “You’ve got to take it one dimension further, and that’s to ask yourself: How will any US redeployment change those dynamics?”

Stephen Biddle, an analyst at the Council on Foreign Relations who has served as an adviser to Petraeus, said on Thursday that he hopes Bush decides to slow down the withdrawal.

“In general, slower is better, subject to the constraint that you not break the military,” Biddle said. “The problem here is that a lot of the violence reduction (in 2007) is attributable to voluntary cease-fires, and if they stopped shooting voluntarily they could start shooting again just as voluntarily.”

At his news conference, Mullen said that in private discussions this week at the Pentagon, the Army chief of staff, General George Casey, and the commandant of the Marine Corps, General James Conway, stressed their concern about the growing, and hard to gauge, strain on troops and their families.

They worry that long and repeated combat tours are wearing out the force, creating excessive strain within military families and possibly, at some point, prompting many to quit the military. Casey, who preceded Petraeus as the top commander in Iraq, speaks of the danger of crossing a “red line” — a point at which the Army no longer will be able to maintain an all-volunteer force.

Underscoring the conflicts between those running the war and those who have to provide the troops for the fight, Conway said on Friday that the Marines “took one for the team” when the Pentagon decided to send 3,200 Marines to Afghanistan for seven months this spring and summer.

There also are about 25,000 Marines in Iraq.

The Corps, Conway warned, cannot maintain the current level of combat deployment for much longer, with Marine units getting just seven months rest at home between seven-month tours to Iraq and Afghanistan.

“We’ll do this through the rest of the year because it’s important,” he said. But he added, “We can’t have one foot in Afghanistan and one foot in Iraq. I believe that would be (analogous) to having one foot in the canoe and one foot on the bank. You can’t be there long.”—AP