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.

Hitler claimed his actions were driven by defense but Britain and France were not buying it. Hitler really thought it would bring lebensraum (living space) for the people of Germany