"In the tribal regions between Afghanistan and Pakistan, the core of al-Qaeda is under more pressure than at any point since it fled Afghanistan nine years ago. Senior leaders have been killed," said John Brennan, chief counter-terrorism adviser to US President Barack Obama.
"It's harder for them to recruit, to travel and train, to plot and launch attacks. In short, al-Qaeda is hunkered down," Brennan said in his speech at the Carnegie Endowment for International Peace, a Washington-based think tank.
As the President said, he noted, it will take time to ultimately defeat al-Qaeda, but it remains a ruthless and resilient enemy bent on attacking this country.
"But we are going to remain relentless in disrupting and dismantling that terrorist organisation, and I can envision the demise of al-Qaeda's leadership and cadre in the coming years," he said.
In his speech, Brennan mainly dealt with the counter- terrorism operations in Yemen and said that America's efforts in that country are part of our larger comprehensive approach to protecting the American people.
"Yesterday, the President provided the American people with an update with regard to our efforts in Afghanistan and Pakistan. As the President said, our core goal remains the same -- to disrupt, dismantle and defeat al-Qaeda and prevent its capacity to threaten America and our allies in the future," he said.
"We're making significant progress towards that goal," he added.
Brennan said the US is helping Yemen build its counter-terrorism capacity for a very specific purpose -- "so that Yemen, with our assistance, can go on the offensive against al-Qaeda."
"Going on the offensive means exactly that – using all the tools available to identify, locate, capture, and, when necessary, kill those who are dedicated to murdering innocent men, women and children," he said.
The relationship between Washington and Sana'a is, at times, marked by differences of view, tension and even strong frustration by each side, he said.
"We frequently push the Yemenis ... to be more aggressive in the actions they take against al-Qaeda for their part...," he said.