Washington (CNN) — The administration’s top counterterrorism adviser said Friday that the al Qaeda group based in Yemen poses a greater threat to Americans than Osama bin Laden’s group based in Pakistan.

John Brennan, assistant to the president for homeland security and counterterrorism, said the Yemen-based group, al Qaeda in the Arabian Peninsula, is “increasingly active” in reaching out to find terrorist recruits, even in the United States.

“Al Qaeda in the Arabian Peninsula is now the most operationally active node of the al Qaeda network,” Brennan said during a forum at the Carnegie Endowment for International Peace.

“The ranks of al Qaeda have been bolstered by members with ties to the West, or with American citizenship, such as Anwar al-Awlaki,” he said. “Indeed, al Qaeda is seeking to attract not just Westerners or Americans overseas, but Americans inside the United States.”

Al-Awlaki is the American-born Muslim who moved to Yemen and has become a key figure in AQAP. He has been linked to the suspect in the Fort Hood massacre of 13 people last year, as well as the suspect in last year’s Christmas Day “underwear bombing” attempt in which a man allegedly tried to detonate an explosive device sewn into his underwear as his flight headed toward Detroit.