Washington:
In the months before Osama bin Laden was killed, the Central Intelligence Agency ran a phony vaccination program in Abbottabad, Pakistan, as a ruse to obtain DNA evidence from members of Bin Laden's family thought to be holed up in an expansive compound there, according to an American official.
The vaccination program was set up as the C.I.A. was struggling to learn whether Bin Laden was hiding in the compound, and adds a new twist to the months of spy games that preceded the nighttime raid in early May that killed the Qaeda chief.
It has also aggravated already strained tensions between the United States and Pakistan. The operation was run by a Pakistan doctor, Shakil Afridi, whom Pakistani spies have since arrested for his suspected collaboration with the Americans. Dr. Afridi remains in Pakistani custody, the American official said.
Getting DNA evidence from the people hiding in the Abbottabad compound would have been a significant coup, because it would have allowed the C.I.A. to match the samples with DNA from other members of the Bin Laden family that are on file at the C.I.A. -- providing the first hard evidence in years of his whereabouts.
The American official said that the doctor managed to temporarily gain access to the compound, but that he never saw Bin Laden and was not successful in getting DNA samples from any Bin Laden family members. Obama administration officials have said publicly they were not sure whether Bin Laden was in Abbottabad when dozens of Navy Seals commandos stormed the house in May.
The existence of the vaccination program was first reported by a British newspaper, The Guardian. A C.I.A. spokesman declined to comment.
It is unclear how the C.I.A. first recruited Dr. Afridi to work for the United States. The Guardian reported that he used a team of nurses and other health workers to administer Hepatitis B vaccinations throughout Abbottabad, even starting the program on poor fringes of the town to maintain a low profile.
Pakistani military and intelligence operatives were furious about the American raid that killed Bin Laden, and relations between the United States and Pakistan have only plummeted since. Pakistani officials have suggested that they might use troops to repel another incursion into Pakistan, and many American officials believe that Pakistan seems more concerned with hunting C.I.A. informants than with finding Qaeda operatives.
American officials said they planned to suspend as much as $800 million worth of military aid to Pakistan -- a move partly designed to chasten Islamabad for expelling American military trainers -- and several influential American lawmakers have suggested attaching more strings to the billions of dollars sent each year to Pakistan.
Also at stake is the C.I.A.'s armed drone program, which has carried out hundreds of strikes in Pakistan in recent years and has killed several senior operatives from Al Qaeda and the Pakistani Taliban. Pakistan has threatened to expel C.I.A. operatives working on the drone program from a base in southern Pakistan, and the C.I.A. has set up contingency plans to run more flights from a base in eastern Afghanistan.
American officials said that they have seen no hard evidence that Pakistani officials knew that Bin Laden was hiding in Abbottabad. However, American intelligence officials said that Bin Laden appeared to have been supported for years by militant groups with longstanding ties to Pakistan's military spy agency.
That agency arrested several suspected C.I.A. collaborators shortly after the Bin Laden raid, but according to the American official only the doctor who ran the vaccination program is still in custody.