Washington (CNN) -- U.S. officials reported the death of an al Qaeda figure identified as the terrorist network's chief of operations in Pakistan, the latest in what they called a series of significant blows to the terrorist network.
Abu Hafs al-Shahri helped coordinate anti-American plots in the region and worked closely with Pakistani Taliban operatives to carry out attacks there, a U.S. official, speaking on condition of anonymity, told CNN Thursday. His cause of death was not disclosed, but the United States frequently uses armed aerial drones to target al Qaeda operatives inside Pakistan.
Al-Shahri was seen as a possible successor to al Qaeda's second-in-command, Atiyah Abdul Rahman, who was killed in late August, the U.S. official said. Little else was immediately known about him.
A senior Obama administration official said al-Shahri was killed earlier this week in northwest Pakistan. Pakistani intelligence officials reported Sunday that a suspected drone strike in the tribal district of north Waziristan, near the rugged border with Afghanistan, had killed three people, but the targets of the strike were not immediately known.
It's the latest in a series of losses among the top ranks of the terrorist network since the U.S. commando raid that killed its founder, Osama bin Laden, in May.
In addition to Abdul Rahman's death, Pakistan's military announced the arrest of Younis al-Mauritani in the Quetta area on September 5. Al-Mauritani was also involved in planning multiple attacks on European countries similar to those in India's financial capital, Mumbai, in 2008, European intelligence officials told CNN last year. The Pakistani military said bin Laden had asked al-Mauritani to target U.S. pipelines, dams and oil tankers.
Bin Laden's replacement, longtime deputy Ayman al-Zawahiri, is the only one of the network's nine top figures at the time of the September 11, 2001, attacks to remain active, Michael Vickers, the U.S. undersecretary of defense for intelligence, said at a counterterrorism conference Tuesday.
Vickers said al Qaeda's leaders "are being eliminated at a far faster rate than al Qaeda can replace them," and their replacements "are much less experienced and credible."
Vickers said al Qaeda's ability to carry out operations from its base in Pakistan could be eliminated within two years -- the first time a senior U.S. official has put a time frame on the end of the threat posed by al Qaeda's senior leadership. But he said affiliated groups such as al Qaeda in the Arabian Peninsula, which claimed responsibility for the failed attempt to blow up a Detroit-bound jetliner in 2009, remain dangerous.
And CIA Director David Petraeus, the former U.S. commander in Afghanistan, told the House Intelligence Committee that al Qaeda is far weaker today than it was 10 years ago.
"Heavy losses to al Qaeda senior leadership appear to have created an important window of vulnerability for the core al Qaeda in Pakistan and Afghanistan," Petraeus said, and the United States will need a "sustained focused effort" to exploit the opportunity.
CNN's Larry Shaughnessy, Pam Benson and Alexander Mooney contributed to this report.