This site posits that antigravity was discovered in the Sputnik-era launch of the United States' own satellite, Explorer I. However, they claim, the discovery was quickly quelled by - who else? - the nefarious Government (with a capital G).
I, of course, have problems with this. Chiefly, how many scientific discoveries (of worth) have ever been dropped? Think about even the most contentious finds of recent years: stem cells, cloning, biological and nuclear weapons... For moral reasons or just plain old self-preservation each has been under attack in hopes of terminating research into these fields with few exceptions. Yet, the research continues covertly, in other countries, and even by our own government. You can't keep - for better or for worse - monumental, life-altering discoveries down.
And an effective way to defy gravity? During the Cold War? Please. More money was thrown at the military complex during the Cold War than before or since. They were wasting it hand over fist on all sorts of worthless inventions with the aim of gaining the advantage. You cannot tell me anyone would have squashed such an enormous discovery with far-reaching economic and military applications.
See, it's not enough to have an outlandish theory but you have to have proof - or at least some logic.