On May 22, 1939, Italy and Germany agree to a military and political alliance, giving birth formally to the Axis powers, which will ultimately include Japan. Mussolini coined the nickname “Pact of Steel” (he had also come up with the metaphor of an “axis” binding Rome and Berlin) after reconsidering his first choice, “Pact of Blood,” to describe this historic agreement with Germany. The Duce saw this partnership as not only a defensive alliance, protection from the Western democracies, with whom he anticipated war, but also a source of backing for his Balkan adventures. Both sides were fearful and distrustful of the other, and only sketchily shared their prospective plans. The result was both Italy and Germany, rather than acting in unison, would often “react” to the precipitate military action of the other. In September 1940, the Pact of Steel would become the Tripartite Pact, with Japan making up the third constituent of the triad.