US Secretary of State Hillary Clinton kept the covert operation to hunt down Osama bin Laden a secret from her husband Bill Clinton, even when she was right inside the White House situation room monitoring the operation. Recalling how he was kept in the dark by his wife who was privy to the secret moves, Bill Clinton said his calls to the Secretary of State went unreturned that fateful day."I placed two calls to my wife on that day, and all I was told is, 'She's at the White House and can't talk to you,'" Clinton said in an interview to CNBC. While discussing US efforts to combat terrorism, Clinton disclosed that despite being close to one of the key decision-makers, he had no inkling of the major operation that was being carried out in Pakistan. "When Hillary got on the Armed Services Committee, which is right after she became a senator, I made up my mind that as long as she was there - and then she became secretary of state - I would never take a security briefing unless asked to do so by the president for a specific reason," Clinton said."And you will be proud that I, like all Americans, knew nothing about the bin Laden operation, which had been debated in the administration in a tiny number of hands for months, until the president called and told me," he added.