The suicide attack at a U.N. guesthouse in which eight people were killed in Kabul last week was a joint operation directed by an Afghan warlord based in the tribal areas of Pakistan and by an operative of al-Qaida, the Afghan intelligence minister said Saturday. The intelligence official, Amrullah Saleh, said eight Afghan suspects had been arrested, including a religious leader who had provided a hideaway for the attackers. He said the suspects had said that the three attackers were all from Pakistan's Swat Valley.