Sputnik was basically Soviet Russia's way of saying "NOTICE ME SENPAI!" to America by launching the world's first artificial satellite.
This is how America responded:
“OMFG u sent a satellite into orbit. big deal we'll send pplz to da moon b4 u. brb we're stockpiling nukes just in case. K bye.”
And thus, the Cold War began when JFK threw a cherry slushie at Khrushchev. Khrushchev then retaliated by throwing a vanilla ice cream cone.