CIA chief: Yemen Qaeda affiliate most dangerous

David Petraeus speaks to the press after being sworn-in as the new CIA Director, in the Roosevelt Room of the White House in Washington, September 6, 2011.

WASHINGTON (Reuters) - Al Qaeda in the Arabian Peninsula, based in Yemen, has emerged as the "most dangerous" affiliate of the extremist group as the terrorism threat shifts to outside South Asia, CIA Director David Petraeus said on Tuesday.

The threat from a weakened core al Qaeda remains a concern for the United States a decade after the September 11 attacks, but the group's vulnerability offers a window of opportunity, Petraeus said in prepared testimony for a joint House-Senate intelligence committee hearing.

"Al Qaeda in the Arabian Peninsula, or AQAP, has emerged as the most dangerous regional node in the global jihad," Petraeus said in his first congressional testimony as CIA chief.

AQAP was behind the December 2009 plot to blow up a U.S. airliner as it approached Detroit and a 2010 effort to send bombs hidden in computer printers on two cargo aircraft, he said.

Political unrest in Yemen has helped AQAP "co-opt local tribes and extend its influence," Petraeus said.

"Despite all of this, counterterrorism cooperation with Yemen has, in fact, improved in the past few months," he said. "That is very important, as we clearly have to intensify our collaboration and deny AQAP the safe haven that it seeks to establish."

While the affiliates are linked to al Qaeda, they have their own command structures, resources, and operational agendas, and largely operate autonomously, Petraeus said.

Southern Somalia has become "one of the world's most significant havens for terrorists" and the al Qaeda affiliate there is large, well-funded, and has attracted and trained hundreds of foreign fighters, including Americans, he said.

The United States continues to face a serious threat from al Qaeda and its worldwide network of affiliates and sympathizers despite heavy losses to the group's senior leadership, Petraeus said.

Al Qaeda leader Osama bin Laden's death in May was a "stunning blow" to the group and his successor, Ayman al-Zawahri, is considered "less compelling as a leader" by the group's followers, he said.

"We thus assess that he will have more difficulty than did Osama bin Laden in maintaining the group's cohesion and its collective motivation in the face of continued pressure," Petraeus said.

A vulnerable core al Qaeda amounts to "a window of opportunity for us and our allies. We must maintain the pressure. We must exploit the opportunity," he said.

(Reporting by Tabassum Zakaria and Susan Cornwell; Editing by Jackie Frank)