President Barack Obama is likely to scale back U.S. ambitions for troubled Afghanistan, redefining victory in a war that his closest military and foreign affairs advisers say cannot be won on the battlefield.

Even before a planned doubling of U.S. forces occupying Afghanistan later this year, the new administration is lowering its sights — and lowering expectations. Although there is general agreement that the United States will be in Afghanistan for years to come, the new focus is on how to show even small security gains and development progress quickly.

"That's clearly the message I'm getting is, 'What are the near-term goals going to be?' " Adm. Mike Mullen, chairman of the U.S. military's Joint Chiefs of Staff, said when asked about Obama's agenda for Afghanistan.

Mullen and Defence Secretary Robert Gates, who has recently suggested the administration of former president George W. Bush overreached in Afghanistan, are scheduled to testify Tuesday before the U.S. Senate and House armed services committees.

Vice-President Joe Biden said the world hasn't done enough to provide economic, political and military resources to Afghanistan, and the United States and its allies lack a coherent strategy. The result is a country backsliding into Taliban control, Biden said.

He warned of higher U.S. military casualties as the Obama administration adds up to 30,000 troops to the Afghan war, where the Taliban is resurgent and where critics say the Bush administration was slow to respond.

"The bottom line here is we've inherited a real mess," Biden told CBS's program Face the Nation on Sunday. "We're about to go in and try to essentially reclaim territory that's been effectively lost."

Obama will refocus U.S. military agenda

Obama has promised to refocus the U.S. military agenda away from what he considers a misbegotten war in Iraq, and last week he called Afghanistan and Pakistan the central front in the struggle against terrorism and extremism.

Aside from transferring troops from Iraq to Afghanistan, he has offered few specifics about how his approach would turn around a fight that Mullen, the nation's top military officer, says the U.S. is not winning.

A few things are becoming clear, however, and none more stark than the notion of what winning in desperately poor, decentralized and deeply traditional Afghanistan would look like.

It is likely to be less about democracy and more about old-fashioned charity and development work. It will be measured by small, local gains in security and governance that give Afghans a reason to reject the efficiencies and protection offered by the Taliban insurgency.

Gates, a holdover from the Republican Bush administration, suggested last week that the previous administration had unrealistic ideas about what it could accomplish in Afghanistan.

"One of the points where I suspect both administrations come to the same conclusion is that the goals we did have for Afghanistan are too broad and too far into the future," Gates said during a Pentagon news conference.

"We need more concrete goals that can be achieved realistically within three to five years in terms of re-establishing control in certain areas, providing security for the population, going after al-Qaeda,... some very concrete things."

Taliban stronger since 2001 U.S.-led invasion

The Taliban are stronger now than at any point since the U.S.-led invasion of 2001, which toppled a Taliban government in Kabul and dismantled some al-Qaeda havens in the country. The Taliban regrouped with help from Islamic militants and factions across the rugged border with Pakistan, and now control chunks of the east and south.

Those militants are now fighting a modern version of an age-old war, relying on the classic insurgent tactics of ambush, assassination and anonymity to tie up a vastly better armed U.S. and NATO force of some 60,000 spread over an anarchic country that sprawls from Iran to China.

Critics of the management of the war include Obama's new national security adviser, retired U.S. marine Gen. James Jones, who last year warned that the U.S. risks losing "the forgotten war."

Gen. David Petraeus, who headed up a renewed U.S. security push in Iraq two years ago, is the latest senior military leader to say that the war in Afghanistan won't be won militarily.

"One of the concepts we embraced in Iraq was recognition that you can't kill or capture your way out of a complex, industrial-strength insurgency," Petraeus said in an interview this month with Foreign Policy magazine.

Petraeus favours deeper outreach to former enemies, and has hinted he would like Iran's help in Afghanistan. The latitude he gets for that effort will be an early clue to the breadth of Obama's planned policy changes.

To that end, Obama has hired a special troubleshooter for Afghanistan and Pakistan whose background is heavy on development and diplomacy. The announcement came at the State Department, the first agency Obama visited outside the White House, with nary a military uniform in sight.

"This is a very difficult assignment, as we all know," envoy Richard Holbrooke said. "Nobody can say the war in Afghanistan has gone well."