Byline: Ron Moreau

As they gear up for a bold new offensive against U.S. forces, the group's fighters strut and plot in plain sight, unmolested by the Pakistani Army or police.

Even before Osama bin Laden's death, Mullah Abdul Qayyum Zakir was working like a man possessed. For weeks the Afghan Taliban's military chief had raced from meeting to meeting in and around his base of operations, the Pakistani city of Quetta. His aim was nothing less than to field the guerrillas' entire fighting strength at once in a massive spring offensive, code-named Operation Badar. If he could just do that, he was sure it would reverse the Americans' past year of battlefield successes in Afghanistan. "He is determined to activate every single Taliban for the first time in 10 years," a senior Taliban intelligence officer tells NEWSWEEK. "He's making it clear that no one will be allowed to sit around in Pakistan. Everyone has to get involved or they're out."

But now Zakir's effort to revive the Taliban's fighting spirit has become more urgent than ever. In the wake of the Americans' late-night commando assault on the Qaeda leader's hideout, veteran insurgents seem stunned and disconsolate--and uncharacteristically worried. "His death is one of the saddest events in my life," says Zabihullah, a senior Taliban adviser. "It conveys a message to all Taliban leaders that no one is safe." The threat looms especially large for Zakir--arguably the Taliban general America most wants dead. A former Guantanamo inmate, he now runs the Afghan rebel group from his base in the Pakistani city of Quetta, where guerrillas strut and plot and live in plain sight, unmolested by Pakistani soldiers or police. He's famous among his men for his almost foolhardy courage, and he seems more than aware that this could be a make-or-break year for the insurgency.

We recently visited the high-desert landscape of southwestern Pakistan's Baluchistan province and its hardscrabble capital city, Quetta, for a close look at how Zakir and his men live. The Pakistani military has declared the province off-limits to U.S. Predator strikes, and the country's Inter-Services Intelligence Directorate (ISI) seems to be giving the Taliban free rein. Old hands among the insurgents say it reminds them of 1980s Peshawar, where anti-Soviet mujahedin operated openly with the ISI's blessing and backing.

Zakir is taking full advantage of his freedom. A tall, dark 38-year-old with intense black eyes and an air of authority, he crisscrosses the province nonstop, usually astride his Honda 125 motorcycle, trailed by a half dozen or so aides and wearing a scarf across his nose and mouth against the ubiquitous dust. Sources close to him say he's been holding eight to 10 meetings a day, from early morning until late at night, not only in Quetta's teeming, impoverished ethnic-Pashtun neighborhoods, but also in small towns and villages all along the bumpy roads to the Afghan border.

His drive, charisma, and raw nerve have made him a very dangerous man. The son of a poor farmer in Helmand province, by 2001 he had become one of the Taliban regime's top military commanders. He was captured during the U.S. invasion that year and ended up at Guantanamo, but he was returned to Afghan custody and finally released in May 2008. He immediately headed to Quetta and rejoined the Taliban, aching to settle scores for his years in U.S. detention. "I have a strong feeling of revenge in my heart," a Taliban subcommander in Helmand province quotes him as saying. "Until this fire of revenge is quenched, the jihad will continue."

Just over a year ago Zakir became head of the Taliban's ruling council, the Quetta Shura, after Pakistani security forces jailed his predecessor, Mullah Abdul Ghani Baradar. Taliban sources say Zakir is a tougher leader than Baradar--more aggressive, more demanding, and hotter-tempered. Baradar was a consensus seeker, in the mold of a traditional tribal chieftain, where Zakir is a warrior above all, seemingly unconcerned about keeping his fellow commanders happy, according to Taliban sources who know him. …