U.S. Military Warns against Hasty Afghan Drawdown

* Military expresses concern about drawdown

* Debate over significance of bin Laden death

* Political pressures vs. battlefield situation

By Missy Ryan

WASHINGTON (Reuters) - As President Barack Obama plans his initial U.S. troop drawdown in Afghanistan, he and his military commanders are offering sharply different takes on how the death of Osama bin Laden will shape the war.

The disparate views, in public comments over the last week, appear to reflect a high-stakes, behind-the-scenes debate over how fast and how far to withdraw U.S. troops from the South Asian country.

Obama, who is expected to announce his decision in coming weeks, on Monday suggested in his most emphatic statement to date that the Navy SEAL raid that killed Osama bin Laden in Pakistan last month may have altered the calculus in neighboring Afghanistan.

Obama vowed he would not order a precipitous drawdown, but said that "by killing bin Laden, by blunting the momentum of Taliban, we have now accomplished a lot of what we set out to accomplish 10 years ago."

On Tuesday, Senator Carl Levin, chairman of the Senate Armed Services Committee and a member of Obama's Democratic party, said the president should withdraw a minimum of 15,000 troops by the end of this year.

"I think the public wants the president to make a significant reduction in troops in July as he said he would do a year and a half ago and reiterated about a month ago," Levin told reporters. His remarks reflected eagerness within the Democratic party to bring the Afghan war to a rapid close.

Obama, with bin Laden dead and significant budget pressure at home, looks set to announce a decision to bring a sizable number of the 100,000 U.S. troops home from Afghanistan, a step toward decisively ending a long, costly war.

But he has not made any final decision, so far as is known, nor even received a recommendation from his field commanders.

Still, U.S. military leaders are warning publicly that a precipitous American withdrawal could endanger hard-won gains against the Taliban and ultimately undermine U.S. security.

U.S. officers say they fear a hasty drawdown and -- in contrast to the White House -- suspect that bin Laden's death may not fundamentally alter the battle against the Taliban, which has long-standing ties to al Qaeda but remains a mainly local insurgency.

Defense Secretary Robert Gates, making a final visit to Afghanistan before he retires later this month, said the impact of bin Laden's death would be clear only later this year. He warned that any major change before the United States can prove it has turned a corner in Afghanistan would be "premature".

Speaking next to President Hamid Karzai, Gates called the U.S. decision to walk away from Afghanistan in the 1990s a "tragic miscalculation" that was laid bare on Sept. 11.

Only recently, he said, has the nearly decade-old campaign in Afghanistan gotten the resources and focus it deserved.

"I think it's way too early to assess, to accurately assess the impact of bin Laden's death," Admiral Mike Mullen, the top U.S. military officer, said last week. "We shouldn't let up on the gas too much at least for the next few months."

STRATEGIC QUESTIONS

Colonel David Lapan, a Pentagon spokesman, said such comments were not a sign of military push-back against the White House in the lead-up to Obama's drawdown decision.

In the end, the Pentagon will get behind whatever option Obama selects. Yet expectations for the initial drawdown vary widely, as some influential lawmakers push for a minimal withdrawal of a few thousand troops and others urging it top 10,000 soldiers.

With hostility mounting in both parties toward the war, which now costs over $110 billion a year, and the 2012 election approaching, Obama faces pressures that may be less compelling for military leaders closer to the fight.

Jeffrey Dressler, a military expert at the Institute for the Study of War, said speculation about divisions within the Obama administration were a distraction from the sole factor that should matter: the situation on the battlefield.

"Frankly, the conditions on the ground do not currently allow for a substantial reduction. A significant withdrawal at the current time risks not only the gains that have been achieved in the south, but imperils a necessary campaign in the east," where fighting has picked up recently, he said.

Brian Katulis, a security expert at the Center for American Progress, said even more important than the initial drawdown were unanswered questions about militants sheltering in Pakistan and efforts to broker a peace deal with the Taliban.

"Our troop presence matters, but not as much as our debate over it seems to imply," he said. (Additional reporting by Phil Stewart, Caren Bohan and Susan Cornwell; Editing by Warren Strobel and Eric Walsh)