Answer:
At the time, it was a vise decision, because Soviets at the time signed the Non-Aggression Pact with Nazi Germany, thus protecting their interests towards Germany.
Therefore, by supporting Britain and France they would enrage Hitler and Stalin was not prepared for conflict with Germany in that moment.
Therefore, it was a wise decision, as he had time to prepare his country to defend his country when eventually Hitler attacks it.
Step-by-step explanation:
Although the pact between Germany and Soviet Union was signed in 1939 just two years later Hitler decided to start Operation Barbarossa.
Attack on Soviet Union was unannounced, but Stalin knew that eventually this will happen.
In that moment Soviet Union was prepared much more to fight of the German forces.