Al-Qahtani is also said to have informed interrogators that he had received operational training in covert communications from Abu Ahmed al-Kuwaiti, whom he identified as a courier for Osama bin Laden. This was an early lead at a time when the hunt for bin Laden by other means had ground to a halt, but, as the national security expert Peter Bergen has noted, it had to be combined with another eight years of work, relying on a wide variety of techniques of intelligence-gathering, to culminate in the US government's 2011 raid on the bin Laden compound in Abbottabad, Pakistan and killing of the al-Qaeda leader.