that the USAF Air Weather Service would use a Lockheed-developed aircraft to study the weather and cosmic rays at altitudes up to 55,000 feet; accordingly, the first CIA detachment of U-2s ("Detachment A") was known publicly as the 1st Weather Reconnaissance Squadron, Provisional (WRSP-1). The death in April 1956, however, of British agent Lionel Crabb while examining Soviet ships in Portsmouth harbor embarrassed the British government, which asked the United States to postpone the Lakenheath flights. To avoid delays, in June 1956, Detachment A moved to Wiesbaden, Germany, without approval from the German government, while Giebelstadt Army Airfield was prepared as a more permanent base. Eisenhower remained concerned that despite their great intelligence value, overflights of the Soviet Union might cause a war. While the U-2 was under development, at the 1955 Geneva Summit he proposed to Nikita Khrushchev that the Soviet Union and the United States would each grant the other country airfields to use to photograph military installations. Khrushchev rejected the "Open Skies" proposal. The CIA told the president that the Soviets could not track high-altitude U-2 flights; this belief was based on studies using old Soviet radar systems and American systems that were not as effective at high altitudes as current Soviet systems, of which the U.S. was not aware. Knutson later said that "the U-2 was really quite invisible to American radar, but Russian radar were a little different—better, you might say". Although the Office of Scientific Intelligence issued a more cautious report in May 1956 that stated that detection was possible, it believed that the Soviets could not consistently track the aircraft. Dulles further told Eisenhower, according to presidential aide Andrew Goodpaster, that in any aircraft loss the pilot would almost certainly not survive. With such assurances and the growing demand for accurate intelligence regarding the alleged "bomber gap" between the U.S. and the Soviet Union, in June 1956 Eisenhower approved 10 days of overflights. The first U-2 overflight had already occurred, using the existing authorization of air force overflights over Eastern Europe. On 20 June 1956, a U-2 flew over Poland and East Germany, with more flights on 2 July. When Eisenhower refused to approve the U-2's flight over Soviet airspace, the CIA turned to a foreign power, MI6, the British Secret Intelligence Service, to request authorization from Prime Minister of the United Kingdom Harold Macmillan, who approved the flights. The fact that radar