Al-Qaeda leaders operating out of Pakistan's tribal belt are planning new attacks against the US which makes it imperative for Pakistan government to take action against the existing sanctuaries in that part of the country, a top American military official has said. Admiral Michael Mullen, the Chairman of the Joint Chiefs of Staff, said the al-Qaeda threat from Pakistan represents a ‘huge challenge’ for the US, and that Pakistan has been lacking in its execution of a strategy to eradicate the safe havens for terrorists and insurgents in its tribal area, according to a report in The Washington Post. Admiral Mullen called on Pakistan to enforce any deals they strike with tribal leaders in the Federally Administered Tribal Area (FATA) and to ensure not only the expulsion of al-Qaeda but also a halt to the flow of insurgents across the border into Afghanistan. "We're just not going to solve it overnight. It's going to take longer than most people realise," Admiral Mullen was quoted as saying by The Post. Meanwhile, Pakistan's new Ambassador to Washington, Husain Haqqani, said US leaders have told his government that if the United States suffers an attack that is traced back to Pakistan, Washington will have to take steps to retaliate. "Those (statements) have been made," Haqqani told The Post, adding, "We want to make sure that it doesn't come to that."