WASHINGTON (Reuters) - A pivotal moment in the long, tortuous quest to find Osama bin Laden came years before U.S. spy agencies discovered his hermetic compound in Abbottabad, Pakistan.

In July 2007, then Senator Barack Obama's top foreign policy advisers met in the modest two-room Massachusetts Avenue offices that served as his campaign's Washington headquarters. There, they debated the incendiary language Obama would use in an upcoming speech on national security, according to a senior White House official.

Pakistan was a growing worry. A new, highly classified intelligence analysis, called a National Intelligence Estimate, had just identified militant safe havens in Pakistan's border areas as a major threat to U.S. security. The country's military leader, Pervez Musharraf, had recently cut a deal with local tribes that effectively eased pressure on al Qaeda and related groups.