The group's last major operation of the war came between 16 January and 19 February 1945. Under Operation Argonaut, the 1st FG escorted British and American delegations to the Yalta Conference, deploying 51 P-38's to protect the ships and aircraft carrying President Franklin D. Roosevelt, Prime Minister Winston Churchill, and their aides to and from the Crimea. The group changed bases shortly after its return to combat operations, moving to Lesina. There the 1st Fighter Group received two YP-80A jet fighters (serials 44-83028 and 44-83029) sent to the theater for operational testing ("Project Extraversion"). Although the jets were marked for combat operations with easily identifiable tail stripes and the letters 'A' and 'B' on their noses, and flown on two operational sorties by the 94th FS, neither saw combat before the end of the war.