日独伊三国同盟
Some countries signed the Anti-Comintern Pact but not the Tripartite Pact. As such their adherence to the Axis may have been less than that of Tripartite Pact signatories. Some of these states were officially at war with members of the Allied powers, others remained neutral in the war and sent only volunteers. Signing the Anti-Comintern Pact was seen as a "a litmus test of loyalty" by the Nazi leadership.