The operation aims to secure Kandahar, the financial, trade and political hub of southern Afghanistan and the seat of Taliban rule of Afghanistan until the 2001 U.S. invasion. Kandahar is the cultural and spiritual center of the Pashtuns, the ethnic group from which the Taliban are drawn almost exclusively.

U.S. and Afghan troops already have made the first moves to flush the Taliban from their strongholds in the lush Arghandab Valley and other districts around the second-largest Afghan city, but a host of problems plague the long-delayed initiative and the larger U.S.-led war effort.

U.S. troops are fanning out across the city of Kandahar to train Afghan police as part of a counter-insurgency plan refined by Army Gen. David Petraeus, the newly named commander of all allied forces, that will focus more on creating a respected government instead of routing insurgents inside the city.

U.S. casualties are averaging two deaths per day, the highest since the beginning of the war, and U.S. troops suffered their highest monthly death toll of the war in July, with 63 Americans killed.

A Gallup poll published earlier this month found that 60 percent of Americans think things are going badly. That was before the massive leak of secret U.S. military reports on WikiLeaks, which drove home what an uphill struggle Afghanistan has been.

Opposition to the war is growing, especially within President Barack Obama's Democratic Party, amid a slow economic recovery and surging federal deficit. On July 27, 102 Democrats in the House of Representatives, all facing re-election in November, voted unsuccessfully to kill $33 billion in emergency war funding.

With mixed signals from Congress and Obama about how long U.S. troops will remain, Afghan leaders say they're uncertain of U.S. intentions.

On the ground, in the face of a determined Taliban assassination campaign, the Afghan government's performance is unlikely to improve. Despite concerted diplomacy and the promise of an enormous new U.S. aid package, the Obama administration can't convince Pakistan to close down the Afghan insurgent sanctuaries that border Afghanistan.

Failure in Kandahar could doom the U.S.-led counterinsurgency operation.

"It is from Kandahar that the Taliban attempt to control the hearts and minds of the Afghan people," said Adm. Mike Mullen, the chairman of the Joint Chief of Staff, in June. "It is my belief that should they go unchallenged there and in the surrounding areas, they will feel equally unchallenged elsewhere.

"As goes Kandahar, so goes Afghanistan," he said.

A major obstacle in Kandahar - and across Afghanistan - is a lack of competent and honest administrators and police who can win the loyalty of the city's estimated 800,000 people and turn them against local warlords and the insurgents.

"Building up formal institutions of government takes a long time," said a senior Western official in Kandahar who also asked not to be identified so he could speak candidly. "So I would certainly hesitate to declare victory too soon on that one."

Kandahar's dominant power is provincial council chief Ahmed Wali Karzai, Afghan President Hamid Karzai's half-brother, who Afghan and U.S. experts say uses his position to control jobs, land and lucrative Western contracts.

Ahmed Wali Karzai, who denies allegations of corruption and drug smuggling, is immensely unpopular, Kandaharis say. Yet the Obama administration appears resigned to working with him following unsuccessful efforts to persuade his brother to remove him.

"What should Kandaharis, who are scared to death right now that they will be killed or bombed, think?" asked Nazif Shahrani, an Indiana University professor of anthropology and Central Asia studies who was born in northern Afghanistan. "Governance without popular support is dictatorship."

To deter Kandaharis from cooperating with the U.S.-led operation, Taliban hit squads are killing an average of one person a day, many of them local officials. The insurgents have attacked NATO convoys, targeted police stations and bombed Western aid groups.

Last month, the district governor of Arghandab was killed by a car bomb, delivering another setback to the campaign.

With summer advancing and the dawn-to-dusk Muslim fasting month of Ramadan looming, Western strategists are lowering expectations for a decisive turnaround before year's end from what's been dubbed Operation Hamkari, or "cooperation" in the Dari language.

"Hamkari is not something you can do for four or five months and stop," said a second senior Western official based in Kandahar who asked not to be identified so he could be more candid.

If all goes as planned, Afghan and American forces hope to control most of the Arghandab Valley by the start of Ramadan next week.

Western strategists are still searching for a definition of success in a battle that they've long argued should be judged more for its ability to install a respected local government and less for how many militants it kills.

"Everyone is asking what success is going to look like - and no one knows," said Cathy Dunlap of the Afghanistan Counterinsurgency Advisory and Assistance Team, a group of outside consultants advising Petraeus.

On a recent afternoon at a new U.S. military outpost dubbed "Hooligan," set up on a road linking the valley with Kandahar city, a U.S. Army officer said progress was difficult to assess.

"It's hard to measure," said the officer with the 508th Parachute Infantry Regiment of the 82nd Airborne Division of Fort Bragg, North Carolina, who asked not to be identified because he wasn't authorized to speak to the media. "It's difficult to tell what success is. It's a big question in Afghanistan."

The U.S.-Afghan military surge is visible everywhere, with convoys rumbling through the province with increasing regularity. American and Afghan forces are setting up a new ring of checkpoints to choke the flow of Taliban fighters, and a surge of civilian strategists into Kandahar city has created a new battalion of experts focused on supporting U.S.-backed politicians.

Western generals are doing all they can to let their Afghan counterparts steer the operation. They consider the fight the latest test for Afghan security forces that remain bedeviled by high illiteracy rates, drug use and corruption.

Senior Obama administration officials insist that they're making progress building up Afghanistan's army, police, judiciary and other governmental machinery, constructing roads, schools and other infrastructure and expanding agriculture and other sectors.

They also cite President Karzai's reaffirmation at a July 20 international conference in Kabul of his commitment to root out corruption and boost governance and accountability, and the backing he received in June at a national peace gathering for reconciling with the insurgents.

Obama has set July 2011 as the start of a drawdown of U.S. troops, who'll number some 100,000 by next summer's end, and the transfer of secure districts to Karzai's government.

Yet violence is raging at an unprecedented level as the Taliban step up attacks on civilians, massive corruption persists, and progress training competent Afghan security forces is fitful.

A report released Thursday by the Senate Intelligence Committee said that Afghanistan's illicit drug trade generates $2.8 billion annually and has become a primary source of financing for the insurgency.

The administration's call for a review of the military situation in December has left Karzai confused, said James Dobbins, President George W. Bush's first special envoy to Afghanistan.

"He's still not exactly sure what the U.S. objectives are," said Dobbins, who just returned from Kabul. Dobbins said that Obama's planned review of Afghan policy late this year shows "explicitly" that the administration may change its policy once again.

In response, Karzai appears to be testing multiple avenues aimed at kick-starting peace negotiations with the Taliban. Yet none of his gestures, including releasing Taliban detainees, requesting the removal of Taliban leaders from a United Nations terrorist list and seeking smoother relations with neighboring Pakistan, have been reciprocated publicly.

Instead, they're fueling dangerous frictions between him and leaders of Afghanistan's ethnic minorities who oppose reconciliation with the Pashtun foes they fought for nearly a decade before driving them from power with U.S. backing in 2001.

Pakistan's military, elements of which are said by U.S. officials to back the insurgency, have declined to move against the sanctuaries on their side of the rugged frontier where Taliban leaders and the heads of allied militant groups direct and supply their fighters in Afghanistan.

"The Pakistanis have to shut down the sanctuaries, but they haven't done it out of their own self-interest," said Walter Anderson, a former State Department intelligence analyst who teaches at Johns Hopkins University's School of Advanced International Studies in Washington.

Anderson was referring to the widely held view that the Pakistani military wants insurgent leaders to form a pro-Pakistan government in Kabul that would prevent Afghanistan from falling under the influence of arch-rival India.