Aug. 7, 2009 -- If the U.S. is able to successfully kill Pakistan's most wanted man, Taliban chief Baitullah Mehsud, it begs the question: Why haven't they been able to do the same to Osama bin Laden, the world's most wanted man?
"Why can't we find bin Laden and why isn't our intel better to ferret him out is a very legitimate question to ask," said Jack Cloonan, a former FBI case agent on the Osama bin Laden and al Qaeda investigations and now an ABC News consultant.
Mehsud and his wife are believed to have been killed early Wednesday morning by a U.S. drone attack when they were on the roof of Mehsud's father-in-law's house in his birthplace of Makeen. Mehsud's death is not expected to be officially confirmed by DNA testing for a few days, but U.S., Pakistani and Taliban officials have all confirmed his death independently.
Cloonan said that while critics may be frustrated that the U.S. is able to locate and kill Mehsud but have not been able to do the same with bin Laden, Mehsud's killing serves as a "reaffirmation to the U.S.'s resolve on the war on terrorism."
"From a tactical point of view, when you have a success like this it shows that the fusion cells that have been set up between special operations on the U.S. side, the CIA and Pakistan are working," said Cloonan.
"In order for you to get someone in a place like [Makeen] it means that ultimately you have to have eyes and ears on the ground and have known that Mehsud would be there ahead of time," he said. "That speaks volume about information sharing."
Farahnaz Ispahani, spokeswoman for Pakistan's President Asif Ali Zardari, suggested that Mehsud presented the imminent threat.
"For many many years now Osama bin Laden has not in any discernable way been active, whereas Baitullah Mehsud has been very active in Pakistan, within our borders, and we have seen on a daily basis the work of his evil and that of his followers," Ispahani said.
According to Joe Elder, a professor of sociology and a specialist on Pakistan at the University of Wisconsin, Mehsud has likely been under extreme surveillance for a long time now, whereas bin Laden has remained a moving target.
"With the assistance of Pakistani intelligence it's much easier to track down and follow the head of the Pakistani Taliban. Many of them have been residing in the region for a long time," said Elder. "It's his home turf, so it's an easier target."
Is Osama Bin Laden Next on Drones' Hit List?
Elder said that while Mehsud's relatives have been known and tracked for a long time, the same has not been possible for bin laden.
"Bin Laden, by contrast, was an outsider who came to Afghanistan but moved about a great deal. He's been on the move for a long time," said Elder. "He's been much harder to follow."
Cloonan adds that the region where bin Laden is believed to be – somewhere near the Pakistan-Afghanistan border – is far more treacherous to search than where Mehsud was located.
"Finding bin Laden is a very, very difficult task in a region that is just so formidable geographically," said Cloonan. "It's a huge expanse, it's largely ungoverned, it's rugged and it's very hard for us to work effectively there."
Cloonan said that the hit on Mehsud will be noticed by bin Laden.
"Don't think for a minute that when a strike like this happens it doesn't have an impact on bin Laden," the former agent said.
Cloonan says that wherever he is, bin Laden is certainly taking extra precautions in the wake of Mehsud's death.
"Bin Laden has to feel as though things are beginning to close in on him," said Cloonan, who has been in touch with people who have met bin Laden in the past. "I believe that he knows that his days as the iconic leader of the Jihad movement are really numbered."
"Anytime we have a successful strike like this, his paranoid has to increase," said Cloonan of bin Laden. "The number of people he trusts will shrink even more and there will be a lot of chit chat among jihadists, particularly in that region, about where the system broke down and who gave up information about Mehsud."
There had been a $5 million bounty on Mehsud. There is a $25 million price on bin Laden's head.
The lethal drones will continue to roam over Pakistan's skies in search of their next targets, and some names are already getting penciled in on their "to-do" list.
Mehsud Strike Makes Others Think Twice of Becoming Jihad Leaders
Already, possibilities for Mehsud's successor -- and possible targets for the drones -- have been identified:
Hakimullah Mehsud, one of Mehsud's deputies and the head of the Taliban in Khyber, Kurram and Orakzai agencies.
Wali ur-Rehman, who has helped control access to Mehsud and acted as a messenger between the Taliban chief and his deputy commanders along the Afghanistan-Pakistan border.
The strike on Mehsud may also have an effect on others considering assuming leadership of jihadist movements.
But among the people who may be vying for the most left empty by Mehsud's killing are individuals who are likely to question whether they want to put themselves at risk, said Cloonan.
"When you take out the head of the Taliban in Pakistan there is going to be a succession battle," he said.
"But some of these warlords are going to start thinking to themselves, 'Am I next?'" said Cloonan. "Even if we think from our side that these people aren't human, at the end of the day there are some people there who really don't want to die."
To locate those people and begin negotiations with them in an effort to gather information about bin Laden and the Afghan Taliban would be a huge feat, according to Cloonan.
"We have to force these people into some sort of negotiation process because we cannot, it's impossible, for us to take out every leader of the Taliban," he said.
"We ought to drive a wedge between them," Cloonan said of the rising Taliban leaders in Pakistan. "Ultimately the game is to work out some sort of agreement that would be the worst thing for bin Laden."
ABC News Nick Schifrin in Pakistan contributed to this report