What was a key outcome of Germany's aggressive actions prior to World War II?

The creation of the Rome-Berlin Axis was a significant outcome of Germany's aggressive actions leading up to World War II, as it represented a formal alliance between Germany and Italy. This pact was forged through shared interests in expanding their respective territories and ideologies, and it signified a united front against other European powers, particularly in light of the growing tensions and militaristic expansions in the late 1930s. The Axis powers coordinated their military strategies and diplomatic efforts, which contributed directly to the escalation of conflict that would erupt in World War II.

In contrast, the other options do not align with the context of Germany's aggressive pre-war actions. The League of Nations was established after World War I in an effort to promote peace, but it failed to prevent the aggression leading toward World War II. The Treaty of Versailles was a peace settlement that ended World War I and imposed heavy reparations on Germany, contributing to its economic difficulties and nationalist sentiments that fueled the rise of aggressive policies. NATO, on the other hand, was formed after World War II as a military alliance among Western nations to counter the Soviet threat, making it irrelevant to the events leading up to World War II.