After killing the al Qaeda leader in a May 2 raid, the United States has made clear it will go after Islamist militants in Pakistan if it finds them, and at the top of any list would be Afghan Taliban leader Mullah Mohammad Omar.
For years, U.S. officials have said the one-eyed Omar is based is in the southwestern Pakistani city of Quetta, not far from the Afghan border, where he heads a Taliban leadership council, or shura.
Pakistan rejects assertions that Omar is in Pakistan, or even that the so-called Quetta shura exists. But such denials ring hollow after the al Qaeda leader was found in the country after years of similar protestations.
People in Quetta are nervous and some are scornful of both sides in the fight against Islamist militancy.
"I have no sympathy at all for Mullah Omar or the Taliban but I have none for the Americans either," said Zulfiqar Tareen, a pharmaceutical company representative taking orders from shopkeepers in one of Quetta's main markets.
"Yes, the Taliban are terrorists but so is America."
Well then, you'd do best to stay out of our way...
For the United States, desperate to find some way to end the nearly decade old Afghan war, catching or killing Omar could prove decisive.
"If they really want to stabilize Afghanistan and Pakistan they should go after Mullah Omar. He is the key," said an Arab diplomat in Pakistan. "It would not surprise me if he is the next target."
Quetta has a population of about 2.5 million, including many Afghans, and sprawls across a flat valley surrounded by rocky mountains.
The city has long been a hub for Afghan refugees and Taliban sympathizers, about 100 km (60 miles) over a mountain pass to the border and Afghanistan's violence-plagued Kandahar province.
Afghan officials say Quetta is a virtual rear base for the Taliban where fighters can rest and get medical care and where their leaders plot. Heavily bearded and turbaned Pashtun men eye strangers with suspicion in some neighborhoods.
Security in the capital of gas-rich Baluchistan province is heavy with numerous checkpoints on roads while guards with rifles slung over their shoulders pace the pavements outside buildings.
But trouble in Quetta comes more from autonomy-seeking separatist rebels than from Islamists like the Taliban.
City hotel worker Nasir Khan said Pakistan should be left out of the U.S. war against the Afghan Taliban.
"Mullah Omar has noting to do with Pakistan, he's just fighting the Americans in Afghanistan, his country ... He's not our enemy so we shouldn't get involved," Khan said.
Despite its reputation as a Taliban hub, there's no obvious militant hold on the city and women make up many of the shoppers in markets where shops sell Indian movies and pop songs.
Whether or not the shadowy Taliban supremo is in Quetta, security officials are nervous.
"It's a very tricky situation," said a senior intelligence official who declined to be identified. "If you ask us if Mullah Omar is in Quetta, the answer is 'no', we have no such information and we are confident about it."
Nevertheless, he said his men had stepped up efforts to track Omar although the had no new leads.
"We'll definitely get him if we know where he is. It's very important for us to get him before the United States does. We don't want another Abbottabad-like situation," he said.
The discovery and killing of bin Laden in the town of Abbottabad, 50 km (30 miles) north of the capital, Islamabad, was a huge embarrassment for Pakistan. The government and military are facing U.S. suspicion that authorities knew where bin Laden was hiding as well as criticism at home for what Pakistanis sees as a violation of their sovereignty by the helicopter-borne U.S. raiders.
There have been no confirmed sightings of Omar since the Taliban government he headed was swept from power by U.S. air strikes and attacks by U.S.-led Afghan fighters weeks after the September 11 attacks on the United States by his ally, bin Laden.
Afghanistan says he is not there but in Pakistan and many people in Pakistan suspect that is right. There has been talk that Omar, fearing strikes by U.S. drone aircraft in Quetta, had gone to ground in the port city of Karachi.
Pakistan, though officially denying support for the Afghan Taliban, has long seen the ethnic-Pashtun dominated Islamists as natural allies in Afghanistan, where most other ethnic and political factions are close to Pakistan's old rival, India.
With Afghanistan entering what could be an end-game as U.S. prepare to begin a withdrawal, Pakistan would likely want to protect its cards, and Omar would be the biggest.