In January 1990, North American Airlines began providing feeder services to El Al's US destinations. El Al held a 24.9 percent stake in the airline until selling it back to Dan McKinnon in July 2003. By this time, El Al was operating a fleet of 20 aircraft, including nine Boeing 747s, and had begun replacing its aging Boeing 707s with the Boeing 757. Early that year, following the collapse of the Soviet Union, El Al inaugurated regular flights to Moscow. No airlifts from the former Soviet Union were possible at the time but permission was granted in 1991. Charter flights commenced in August 1991, with immigrants also occupying all available seats on El Al's scheduled routes. In cooperation with Aeroflot, El Al flew more than 400,000 Jewish immigrants to Israel within a three-year period.