expected delivery path. For example, the first steps of the final arming process for a ballistic missile depend on physical characteristics of the weapon release, such as the acceleration of a rocket launch, zero-gravity coasting, and various physical aspects of hypersonic reentry into the atmosphere. A gravity bomb dropped from an aircraft will detect the altitude of release and the decreasing altitude as it falls. Journalist Ron Rosenbaum has pointed out that the SIOP is entirely concerned with the identity of the commanding officer and the authenticity of the order, and there are no safeguards to verify that the person issuing the order is actually sane. "The president has supreme authority to decide whether to use America's nuclear weapons. Period. Full stop," says the Arms Control Association's Kingston Reif. A president could only be stopped by mutiny, he explained, and more than one person would have to disobey the president's orders. Notably, Major Harold Hering was eventually forced out of the Air Force for asking during his missile training course how he could know that an order to launch his missiles was "lawful," that it came from a sane president, one who wasn't "imbalance[d]" or "berserk." United Kingdom participation Although after World War II the formal military alliance between the United States and United Kingdom no longer existed, American postwar war plans required using British air bases until the United States developed ICBMs and long-range bombers. American General Carl Spaatz and Chief of the Air Staff Lord Tedder informally agreed in 1946 to US aircraft using British bases. The discussions, and the subsequent actions such as extending runways, were so secret that it is unclear whether Prime Minister Clement Attlee was aware of them. By 1948, the year of the Berlin Blockade, British leaders expected that "in a future world conflict, US and British forces will find themselves fighting side by side" although the alliance had not been formally renewed. The two countries began coordinating their plans for a Soviet attack in Europe after the Czechoslovak coup d'état of 1948, and later that year General Curtis LeMay, head of Strategic Air Command (SAC), asked Tedder to allow the basing of American atomic weapons in Britain. By the end of 1948, several British bases were atomic-capable or were close to being so, but the ability to fight an atomic war from Britain did not exist until April 1949 when Silverplate B-29