I can't figure this out. Communism was supposed to be against nationalism. This would seem to favor pan-Arabism, which espoused the ideal of uniting the Arab lands instead of remaining divided up more or less in the same way as the British and French had established.
I could be mistaken but this conflict seems to predate Brezhnev. Khrushchev seems to engage in the conflict too, with at least one exception, and it maybe even goes back to Stalin. So it does not appear to be linked to any leader's new doctrine or reform change.
So what were the ideological and historical reasons for these two movements being at odds with each other? Was it more of a realpolitik thing?