Both Czarist Russia and the post revolution Russia were allied with the West in WWI. The Soviets took Russia out of the war. In addition their political philosophy/religion was antithetical to that of most if not all western powers. Even then the support given the Whites was rather limited but for the same reasons distrust was rather a two way street. Then there's the whole thing about the Boshevik's wanting to see a "Communist" world government. With them as first among equals of course. Their actions essentially provoked negative reactions from the west and the lack of "trust" was there prior to said reactions. After all Monarchist and Capitalist were the demons of Marist dogma.
Distrust was definitely a two way street. Both, however; realized that it was Germany which was the immediate threat.
It was a compromise between morality and expediency. During the Winter War the British and French prepared an intervention force to support Finland. Perhaps fortunately, hostilities ended before the british and Frecnh found themselves fighting both Nazi Germany and the USSR. When Hitler invaded the Soviet Union Churchill made hsi famous devil quopte
Even more incredibly they were just weeks away from bombing the oil fields of Baku, but Hitler attacked France, and they were forced to focus their attention there. Setting the place on fire, destroying their main source of oil would really make the Soviets mad.
