Osama bin Laden was in Pakistan as recently as last month and met there with his chief operational lieutenant, Pakistani security officials said today. The officials said material seized on Saturday during the arrest of the lieutenant, Khalid Shaikh Mohammed, showed that Mr. Mohammed met with Mr. bin Laden sometime in February, possibly in Rawalpindi, the city adjacent to Islamabad where Mr. Mohammed was discovered on Saturday. “There is now no doubt that he is alive and well,” a senior Pakistani government official said of Mr. bin Laden in an interview. “We have documents that show he is alive and in this region.” Officials in Washington said today that they knew of no specific information that would show the two men had recently met. But they saw a meeting between the terrorist leader and his main lieutenant as plausible and said it would suggest not only that Mr. bin Laden remained in charge of the terror organization but also that planning was under way for a major attack. Mr. bin Laden has eluded a worldwide manhunt for more than a year. American authorities have been uncertain of his location since the American bombing of his hideout in Tora Bora, a mountainous region of Afghanistan, in late 2001 — though he is believed to have escaped the attack. American intelligence officials have ascribed two recently released audiotapes to Mr. bin Laden, but firm proof of his survival has remained elusive. The senior Pakistani official said the information that Mr. bin Laden and Mr. Mohammed met in February came from documents, CD-ROM’s and a computer discovered at the time of Mr. Mohammed’s arrest. Full Story