His military power and the communistic approach go hand in hand, without one he would not have the other.
Uhm....while there was a small Community party in Cuba, founded in the 1920s, before Castro came to power, he WAS NOT part of that group. In fact, in 1959, when Castro came to power, Soviet premier Khrushchev asked the Cuban Communists about him, and they said he wasn't affiliated with. At that time, Castro referred to the government system as "Socialism".
He gained his military power *BEFORE* he became a communist!
1959 (Jan) - Casto comes to power (not Communist); Khrushchev begins discussions
1959 (Oct) - U.S. begins planning overthrow of Cuban govt
1959 - Castro's ex-lover Marita Lorenz fails as CIA-backed assination attempt
1960 - Cuba begins buying oil and goods from USSR; later comes military aid
1961 (Jan) - Eisenhower breaks off political ties with Cuba
1961 (April) - Bay of Pigs invasion (1,400 CIA Mercenaries)
1961 (July) - Castro's "26 July" movement merges with a Cuban socialist group
1961 (Dec) - Castro says he's "Marxist-Leninist" and that Cuba was adopting Communism
1962 (Feb) - U.S. begins trade embargo
1962 (March) - Castro's Group becomes "United Party of the Cuban Socialist Revolution"
1962 (Oct) - Cuban Missle Crises
1965 (Oct) - Castro's Group becomes "Communist Party of Cuba"
So as you can see, Castro was a pain-in-our-ass before he "switched" from Socialism to Communism. We tried to invade Cuba before he was a Commie. We tried to kill him off before he was a Commie. We cut off political ties before he was a Commie.
The embargo isn't about Communism itself--again, if that were the case, we'd be against Communism everywhere. No, it's about the pain-in-the-ass factor of Castro himself and his connection with Khrushchev.
Heck, the reason so many U.S. politicians are in favor of disolving the embargo today is because of the end of the Cold War, the fall of the USSR, and the lack of any immediate threat from Cuba.
But if it did end today---Castro would still be Communist!