How did the expansionist ideas of hitler stalin and tojo lead to ww2?

 Hitler marched his troops into the Rhine, the Sudetenland, the rest of Czechoslovakia, and Austria over the protests of Britain, France, and the US. On Sept. 1, 1939, Nazi Germany invaded Poland, thereby starting WW2 in Europe. The Poles fought valiantly against Hitler's forces; when they took refuge behind the Vistula River, and it seemed they could hold on until the arrival of the British and French, Stalin entered the war and invaded Poland from the east. About 2 weeks later it was all over for the Poles. 
Stalin also invaded Finland on the flimsy pretext of protecting his northern frontier. The Finns, although outnumbered and outgunned, held off the Soviets for several months. 
Japan annexed Korea in 1910. The militarists of Japan also invaded Manchuria (China) in 1933, trying to create what they called the "Greater East Asia Co-Prosperity Sphere." In their delirious minds, they thought that Asia would thrive if all of it was under their rule. The rest of Asia disagreed. Japanese brutality in Manchuria caused the US to enact a trade embargo against Japan. The Japanese used the embargo as an excuse for the attack on Pearl Harbor on Dec. 7, 1941, thereby precipitating America's entry into WW2.