By MARK MAZZETTI


“Anyone can be snookered and doubledealt. But after six years you have to start to figure it out.”

WASHINGTON - Bruce Riedel was a 28-year-old Middle East analyst at the Central Intelligence Agency on October 6, 1981, the day a band of gunmen assassinated President Anwar el-Sadat of Egypt during a military parade in Cairo.

Within hours of the attack, Mr.Riedel was summoned to the agency’s seventh floor to brief William J.Casey, the irascible C.I.A. director. Over the next several months, he began compiling a dossier about the attack - what he calls the “birth of the global jihad” - and about the emergence of a cerebral Egyptian physician named Ayman al-Zawahri.

He retired from the C.I.A. in 2006 after 29 years, and no longer has access to the nation’s most sensitive information. But his career as an analyst is far from over. As an influential terrorism adviser on President-elect Barack Obama’s transition team, he dispenses counsel to the administration-in-waiting on some of the thorniest problems it will face: as varied as the hunt for Al Qaeda’s senior leaders like Mr.Zawahri, the likelihood of another attack on American soil, and how to stave off nuclear Armageddon between India and Pakistan.

Mr.Riedel is one of a chorus of terrorism experts who see the terrorist network’s base in the mountains of Pakistan as America’s greatest threat, and perhaps the biggest problem facing Mr.Obama.

He speaks angrily about what he calls a savvy campaign by Pakistan’s government under President Pervez Musharraf to fleece Washington for billions of dollars even as it allowed Al Qaeda to regroup in Pakistan’s tribal lands.

“We had a partner that was double-dealing us,”he said during an interview in his house in a Washington suburb.“Anyone can be snookered and double-dealt. But after six years you have to start to figure it out.”

His new book,“The Search for Al Qaeda,”jabs at the Bush administration for diverting troops and resources from Afghanistan to Iraq, and for a byzantine intelligence apparatus that“lacks a sheriff to lead the posse” in the hunt for Qaeda operatives.

He believes that the terrorist network is hoping the United States keeps troops in Afghanistan and Iraq for the long haul.

Washington must approach Pakistan with a“subtle and deft touch,”he said, and strengthen the civilian government of President Asif Ali Zardari, the husband of Benazir Bhutto, the slain former prime minister, to act as a counterweight to Pakistan’s military and intelligence apparatus, which still dominates political life.

Some of his former C.I.A. colleagues describe him as unflappable and usually eager to champion a dissenting analytical view.

“There are a lot of people at C.I.A. who were more wedded to traditional ways of thinking who butted heads with Bruce, and he certainly has his share of people there who don’t care much for him,”said Kenneth Pollack, who worked with Mr.Riedel both at the National Security Council and the C.I.A. and is now his colleague at the Saban Center for Middle East Policy at the Brookings Institution.

Today he is in lockstep with his former C.I.A. colleagues on at least one matter: the necessity for Pakistan’s preeminent spy agency, the Inter- Services Intelligence, to sever its longstanding ties to militants operating in Pakistan’s tribal areas. These are ties the Bush administration never found a way to break, as the ISI has used the militants as a proxy force there for decades.

And they will not be broken, Mr.Riedel said, until Pakistan’s generals and spy agencies acknowledge what the president learned only through heartbreak - that the struggle against Al Qaeda and its ilk is“their war”as much as it is America’s.

“Zardari knows it’s his war, because he buried his wife,”he said.“That tragedy is also an opportunity.”