I didn't say it did? Remember, we're discussing why Cuba ended up so closely allied to the Soviet Union - not what started everything. If you really want to pull that thread the "Soviet involvement" in Cuba started after the revolution when the US rebuffed Castro's attempts to reach out and meet with Eisenhower. There were of course many contributing factors that caused Cuba and the USSR to end up so close, but I think it's safe to say the ongoing blockade set everything in stone and all but guaranteed it until the latter's collapse (barring a brief period where JFK appeared to favour rapproachement with Cuba before his assassination).