While its contribution to SIOP was minor compared to the enormous SAC arsenal of 1,600 bombers and 800 missiles, as RAF officers who worked with the Americans rose to leadership positions their experience benefited later partnerships between the two countries. The joint targeting plan changed over time; the 1962 list for the RAF included 48 cities, six air-defense sites, and three bomber bases, and the 1963 list had 16 cities, 44 airfields and other offensive sites, 10 air-defense sites, and 28 IRBM sites. The degree of cooperation was such by the Cuban Missile Crisis that RAF officers visiting SAC headquarters in Nebraska reported being "treated just like Americans. We went all through their briefings, computers, top secret rooms and so forth". While some British officers emphasized the continuing importance of maintaining the ability to act alone with an independent deterrent if necessary, by 1962 the independent list was essentially the RAF portion of the joint plan and no active training was done. The British emphasis on retaining an independent capability, however, continued over several decades and changes in government. As the Defence Council stated in 1980,