Osama Bin Laden
US worked solo on Bin Laden operation as it was unsure about Pak's loyalties: former CIA director Pictured: Osama bin Laden is shown in this video frame grab released by the U.S. Pentagon.Reuters

The U.S. worked alone on the operation against al Qaeda leader Osama bin Laden as it did not trust Pakistan, former CIA director Leon Panetta said after the fifth anniversary of the operation that took out the terror group's head in Abbottabad, Pakistan.

Panetta, in an article in the Harvard Business Review, wrote how the CIA had to let go of its assumptions that the terrorist would be hiding in a rural cave, surrounded by his men. Instead, they found leads in August 2010 about his Abbottabad residence, which was a villa near a Pakistan military base.

"Pakistan was difficult because they had a close relationship to various terrorist networks, and you were never quite sure just exactly where their loyalties would lie," the Press Trust of India quoted Panetta as saying in an interview to PBS news. He said: "There were so many questions raised about whether or not we could trust them that the president [Barack Obama] decided that we should do it alone."

In his article he penned for the Harvard Business Review about the managerial process of the large-scale operation, Panetta said: "The team conducted the raid flawlessly, killing both brothers [who acted as couriers for Laden], heading up the stairs of the main compound, killing bin Laden's adult son Khalid, and finally killing bin Laden in his bedroom on the villa's third floor."

The former CIA director's article comes days after the CIA "live tweeted" the operation that killed bin Laden in his house in Pakistan. However, the "live tweets" received some criticism from netizens who called it "bizarre" and "grotesque."

Panetta also said terrorism lives on five years after bin Laden's death, though the al Qaeda has "metastasised."

On the U.S.' relationship with Pakistan, he said the two countries did work jointly on intelligence and military fronts.

"We have done a very good job at decimating al Qaeda's leadership, particularly in Pakistan. And obviously, the bin Laden operation was kind of the primary effort to go after the spiritual leader of al Qaeda," he was quoted by PTI as telling PBS News.