In October Kennedy learned that the Soviet Union had moved first-strike missiles, along with Soviet experts and troops, into Cuba. Although these were medium and intermediate-range missiles, their placement 90 miles from the United States border meant they could strike virtually any city in the States or attack allies in Central or South America. The world held its collective breath for 13 days after Kennedy demanded that the Soviet Union remove the missiles. When Kennedy ordered the 550th Strategic Missile Squadron to place the 12 missiles at Schilling Air Force Base on alert, the Utah Construction workers who had built and lined the missile silos must have experienced a heightened tension. Following a Naval quarantine and blockade of Cuba, as well as verbal pyrotechnics in the General Assembly of the United Nations, Kennedy and Khrushchev reached accord. The missiles in Cuba were dismantled and removed. To fulfill a secret promise to Khrushchev, Kennedy later removed obsolete Jupiter missiles from Turkey, near the border of the Soviet Union. At left, an Atlas intercontinental ballistic missile rises over its silo during a test.