WASHINGTON, Feb 17: Pakistan's cooperation has helped keep Al Qaeda at its weakest point since 9/11, say US intelligence chiefs, but they also complain that the country's reluctance to take action against certain other groups frustrates America.During a testimony at the US Senate Select Committee on Intelligence, CIA Director Leon Panetta described the US-Pakistan relationship as “very complicated” and acknowledged that the two countries often differed on various issues. “One of those complicating issues is the fact that they're a nuclear power,” he said. “They have a number of nuclear sites throughout their country, and they have proceeded to keep up development of their nuclear weapons.”

Mr Panetta and US National Counter-terrorism Centre Director Michael Leiter underlined their frustration with Pakistani intelligence services.

The committee's chairwoman, Senator Dianne Feinstein, commented that the ISI “walks both sides of the street”, helping the United States at times, but refusing to hand a key suspect in the 2008 Mumbai terrorist attacks to India and hesitating to send forces to fight the Taliban in North Waziristan.

“They look at issues related to their national interest and take steps that complicate the relationship”, Mr Panetta said. He acknowledged spending significant time discussing “how they operate, the ties they have to certain groups” with his Pakistani counterparts. “Pakistan's cooperation has helped keep Al Qaeda at its weakest point since 9/11,” Mr Leiter said. But resistance in other areas, including relationship with LeT, frustrated the US, he added.