Since arriving in Afghanistan one year ago, Gen. Stanley McChrystal and his staff have had their eye on one prize above all others: the southern province of Kandahar, the ancient fault line between civilizations where the Soviet Union lost its final battles, the Afghan Taliban was born, and where the group first reemerged after the U.S. invasion.
Over the next few months the U.S. presence in Kandahar will crescendo into Operation Hamkari Baraye Kandahar -- "Cooperation for Kandahar" -- an attempt to protect residents from insurgents and provide them with a functioning government. It will feature tens of thousands of American troops and hundreds of civilians, the single largest operation since the war began.
U.S. commanders have struggled to find a crisp description of the campaign, reaching for phrases like "a series of activities," "thickening the battlespace," "restoring order," and "a rising tide of security."
But they have agreed on its paramount importance: the campaign is aimed at the Taliban's spiritual heartland. It has no backup plan, and it must show immediate results before the White House reviews its Afghan policy in December.
"Our intent is to take away from [the Taliban] access to the population where they are traditionally strongest. And that will take away from them some of their credibility as well as recruiting, funding, access to narcotics," McChrystal told ABC News in a March interview. "It won't be decisive. But it's a pretty severe blow to them if they lose what we would consider their most important area."
Many have been more blunt. The campaign is the most significant test of the new American counterinsurgency strategy in Afghanistan, and if it fails in any way, risks further alienating a skeptical population that is desperate for security.
"We've got a few months," says one senior military official who has helped plan the campaign, "to make a giant difference."
Geographically, the campaign will focus on three areas: the rural districts outside Kandahar City that insurgents have used as staging grounds; the circular edge of the city; and the city's heart.
In many ways, the campaign becomes increasingly challenging as it moves toward the center of the provincial capital. Unlike the Marja operation, where U.S. Marines invaded an area, cleared it of a few hundred Taliban, and set up a government and an economy largely from scratch, the U.S. Army will not roll its armored vehicles into the city of 1 million residents. That has to be left to the Afghan police, which is still struggling to find autonomy.
"The Heart of Darkness"
And the U.S. has to work with the political infrastructure that's already there, mentoring and cajoling district and provincial governments that have been ineffective, severely under-resourced, and in some cases, corrupt. Without a functioning city and provincial government, U.S. military officials admit their successes will not produce substantive improvements in Afghans' lives.
"It's all about the government, it's all about the police," says the senior military official. "This is the Afghan government's to win or lose. There's enough combat power from a military standpoint to do what we need to do."
The vast majority of that combat power will go to the districts surrounding Kandahar City. Half of "Greater Kandahar" lives in those areas, which will likely host a long, hot, violent summer.
ABC News spent three weeks in the districts of Maiwand and Zhari. Zhair was so feared by the Soviet Army it was dubbed "the heart of darkness." Residents of Zhari consistently said in interviews there was little stopping insurgents from moving around and little to no presence of the Afghan government. The main reason: there has not been enough troops -- American, Canadian, or Afghan -- to protect people from the Taliban. Multiple village leaders were scared to be seen with American soldiers, knowing when they left, insurgents would come to threaten them.
"This is the home of the Taliban. This is an area that has provided a lot of the leadership for the Taliban movement, not only local and mid-level leaders, but senior leaders, Mullah Omar himself," said Lt. Col. Jeffry French, the commander of the 2nd battalion of the 5th Stryker Brigade Combat Team, which is currently in charge of western Zhari.
Two of the battalion's outposts sit within a few miles of Sangisar, the town where Mullah Omar used to live and where he took the oath from a few dozen men that started the modern Taliban movement in 1994.
"This is the staging area for Kandahar City. They have operated with impunity here," French says, although the arrival of a company of his troops in western Zhari just before Christmas has improved security. "I don't think there's any greater effect we could have on the Taliban's ability to pursue the war than establishing persistent security here."
"Blanket of Security"
But French and local leaders admit the challenge will be massive.
"Zhari is like the gateway to Kandahar city," says Mohammed Niyaz Serhadi, who was the Zhari district governor until he recently resigned in order to run for parliament. "Most of attacks are planned in this district. Most of the government opponents are based in this district."
Serhadi admits neither he nor the police have very much reach in Zhari. He spoke to ABC News last month in the Zhari district center, which is located inside an American army base because of threats.
"The government doesn't even have control of 10 percent of the district," he said.
The thousands of troops moving into Zhari and the surrounding districts will try to disrupt Taliban safehavens, just as U.S. troops did around the Iraqi capital as part of the surge there in 2007.
"Just like Baghdad, somewhere out in environs, we had enough forces hitting where they were building the IED's, where they're causing most of the problems for the city, where they're coming from," says a separate senior military official. "With enough forces out there [we can] get security well stabilized" in the city.
Between the districts and the city center the United States will try to create a "blanket of security" or "an outer ring of security," according to senior military officials. Thirty-seven roads lead in and out of the city, and up until this point, the Afghan police been unable to keep militants from coming in and out.
The U.S. and the Afghan police will try to do that with new checkpoints, some of which are woefully inadequate right now.
"I think there's one that's a dude with a lawn chair," a senior military official in Kandahar recently quipped, only half joking.
The City Center
The relative ease with which Taliban have infiltrated the city has led to a terrifying and precise campaign of intimidation and assassination.
More than two dozen local leaders have been killed in and around the city this year, including the deputy mayor as he prayed in a mosque.
U.S. officials admit what residents repeatedly complain about: there is nothing stopping the Taliban from sending a threatening "night letter" to a family that works for the government or coalition troops, and then following up on that threat with a volley of bullets.
Americans Training Afghan Cops to Control Kandahar City
"Right now you don't have population control," the senior military official in Kandahar says. "But that can't be done by the U.S. or the Canadians."
That's because any significant presence of Western troops in downtown Kandahar would mean violent, daily clashes in extremely crowded neighborhoods. The toll on the population would be too high.
So U.S. Military Police are training Afghan police inside the city, and those efforts will be redoubled to try to produce a competent, independent police force.
"We're pedaling as fast as we can to get them trained," the senior military official says, "but we're not where we need to be yet."
The U.S. and the provincial government are also working to improve basic physical security for important buildings in Kandahar City, such as the vulnerable police station that "even Ray Charles could find," in the words of a separate senior military official.
In the end, the complex collection of fighting in the districts, checkpoints around the city and training and physical security enhancements inside the city will all have to work at the same time for the U.S. to see the kind of results it needs to quickly. U.S. commanders say they want to see visible improvements by the time Ramadan begins in the middle of August.
And much of it will be dependent on whether the local governments can improve -- and provide residents with the confidence that the U.S. and powerful Afghans are fighting to secure the population.
"How do you show success in this campaign?" asks a senior civilian official in Kandahar, referring to the new U.S. strategy in Afghanistan. "You stabilize Kandahar."
ABC News' Luis Martinez contributed to this report