Space race

Sputnik.

I'll agree with califdadof3. The Americans obtained missile technology (developed by the Germans) after occupying Germany following WWII. Nuclear warheads can be fitted to these missiles for long range attacks. (although not as long-range as modern ICBMs) After Sputnik was launched, the Americans feared that the Russians would be able to deploy nukes directly from space. Therefore, the Space Race began. I'm not expert on history so I may be wrong but this is just my analysis.

Pretty much everybody got a German expert or two - not just America. Most likely there was a quite technology race going on for some time, but since the American public had no real clue about Russian capability, Sputnik was the first firm evidence of Russian progress.

The space race was not just a military race but a propaganda race of Russia versus USA and Communist versus Capitalism.