Newly declassified documents released from the British National Archives show that U.S. President Ronald Reagan had offered Margaret Thatcher a chance for both countries to work on the F-117 stealth program back in 1986.
By United States Air Force [Public domain], via Wikimedia Commons
The program was given the code-name Project Moonflower and the British Ministry of Defence declined the offer to buy the F-117 as it was still a black program.