Lazer-Hound
The USAF exchange guys were probably not allowed during Corporate due to the fact that the USA was technically supporting the Junta in Argentina with kit (A-4, C-130 etc) to help their fight against their distinctly left leaning South American counterparts. Hence the supply of the latest Sidewinder for the SHARS being kept quiet. No official support of the UK by the USA who were also trying to broker a peace deal IIRC.
I guess the USA was a bit worried we might use the Vulcan properly on Buenos Aires and take out an ally in the fight against communism in South America.