What Is It? - Tunguska

I believe that the Tunguska explosion was caused by a nucleur weapon that the Soviet Union tested. My three pieces of evidence are-

1.) The scientists found several similarites with this attack and the one on Hiroshima; this is the only thing they've been able to compare it too.
2.) There were no craters so a meteor is ruled out; there were only flattened trees which could be caused by a nucleur attack.
3.) The Soviets were Communists back then and had a secret police; there's quite a possiblity that they could've been testing this material long before us.