Washington:
Ayman Al Zawahiri, who took over the leadership of al Qaeda after the death of Osama bin Laden last year, remains in the Af-Pak region, a top US counter-terrorism official said on Sunday.
"We believe he (Zawahiri) is in that region of the world, as well as other al Qaeda leaders that continue to borough into areas of...the Federally Administered Tribal Areas of Pakistan. That's why we're working very closely with our Pakistani partners," John Brennan, the Deputy National Security Advisor to US President Barack Obama, told CNN in an interview.
"We're not going to relent until they're brought to justice one way or the other," Mr Brennan said responding to questions on the whereabouts of al-Zawahiri.
"We demonstrated the ability to do that with bin Laden. We are in constant consultation with our Pakistani counterterrorism partners on a regular basis about how we can do this as soon as possible," he said.
Mr Brennan also acknowledged that al-Zawahiri is now the number one target of the US.
"They have to go. It's an organization that's dedicated to murder and mayhem and we as well as other countries of the world are determined to make sure that that happens," he said.
Al-Zawahiri took over as al Qaeda chief about a month after bin Laden was killed by US Navy SEALs in a covert raid in Abbottabad on May 2 last year.
The US is also focused on the al Qaeda in Yemen, he said.
"There are leaders of al Qaeda in the Arabian Peninsula that we are focusing on. And we're trying to make sure that they're brought to justice. Again, one way or the other, we're going to work closely with our Yemeni partners," he said.
"Al Qaeda in the Arabian Peninsula, which is located in Yemen, is involved in a very active insurgency against the Yemeni government. And we're working closely with the Yemeni government, their security, intelligence, and military forces, to ensure that that growth of al Qaeda in Yemen can be blunted," Brennan said.
"At the same time they've demonstrated as well as the capability to try to carry out attacks against the homeland. You know Umar Farouk Abdulmutallab with the underwear bomber as well as the printer cartridge caper," he said.
"So what we're trying to do is to make sure that they're not able to carry out those attacks. But we have to work very closely with the Yemenis. We're doing everything in Yemen in full cooperation with our Yemeni partners. We are going to do that," he said.