Germany, under the leadership of Adolf Hitler, pursued an aggressive policy of territorial expansion known as Lebensraum ("living space"). This involved the annexation of Austria and Czechoslovakia in 1938 and 1939, respectively, and the invasion of Poland in September 1939, which is widely considered the start of World War II.
Italy, led by Benito Mussolini, engaged in expansionist campaigns in Africa, particularly in Ethiopia, and in the Mediterranean. In 1940, Italy invaded Greece and Albania, further escalating tensions in the region.
Japan, under the influence of militarist leaders, embarked on a series of conquests in Asia. This included the invasion and occupation of Manchuria in 1931, the Second Sino-Japanese War from 1937 to 1945, and the attack on Pearl Harbor in December 1941, which drew the United States into World War II.
The aggressive expansion of Germany, Italy, and Japan created a sense of insecurity and fear among other nations. Their actions challenged the existing international order and contributed to the outbreak of the Second World War.