Which factor most contributed to nazi germany’s decision to invade poland in 1939

The major factor for Hitler's invasion of Poland was the signing of the German-Soviet  pact. It was also known as Molotov-Ribbentrop Pact. It was a non-aggression pact in which the countries agreed not to take any military action against each other for the next ten years. While for the Stalin it was a way to maintain peace with Germany but for Germany, it was an assurance of an unopposed invasion of Poland. With the pact, several secret agreements were made about the later Division of eastern Europe. The agreement broke down in 1941 when Hitler invaded Soviet Russia.

when world war i broke out across europe in 1914, president woodrow wilson proclaimed the united states would remain neutral, and many americans supported this policy of nonintervention. however, public opinion about neutrality started to change after the sinking of the british ocean liner lusitania by a german u-boat in 1915; almost 2,000 people perished, including 128 americans. along with news of the zimmerman telegram threatening an alliance between germany and mexico, wilson asked congress for a declaration of war against germany. the u.s. officially entered the conflict on april 6, 1917.