This high-speed, high-altitude approach was effective until the late 1950s, when the Soviet Union began to introduce its first surface-to-air missiles (SAMs). SAMs had speed and altitude performance much greater than any contemporary aircraft. The Canberra, and other high-altitude aircraft like the V bombers or United States' B-52 Stratofortress, were extremely vulnerable to these weapons. The first aircraft to fall victim to the Soviet S-75 "Dvina" (NATO name "SA-2 Guideline") SAM was a Taiwanese RB-57, a US reconnaissance version of the Canberra, shot down in 1959.