The facility was established to hunt for members of al-Qaeda in the Arabian Peninsula, which is based in Yemen.
A drone flown from there was used in September 2011 to kill Anwar al-Awlaki, a US-born cleric who was alleged to be AQAP's external operations chief.
US media have known of its existence since then, but have not reported it.
Senior government officials had said they were concerned that disclosure would undermine operations against AQAP, as well as potentially damage counter-terrorism collaboration with Saudi Arabia....
...The Washington Post reported
that President Barack Obama's counter-terrorism adviser, John Brennan, a former CIA station chief in Saudi Arabia, played a key role in negotiations with the government in Riyadh over building the drone base.
Senators are expected to ask Mr Brennan about drone strikes, the memo and the killing of Awlaki when he faces a confirmation hearing on his nomination to become the new CIA director on Thursday.