What was a primary outcome of the use of atomic bombs on Japan in 1945?

The use of atomic bombs on Japan in 1945 resulted in the immediate and profound impact of hastening the end of World War II. The bombings of Hiroshima on August 6 and Nagasaki on August 9 led to Japan's unconditional surrender on August 15, 1945, effectively concluding the Pacific Theater of the war. This act marked a critical turning point; not only did it bring about an end to hostilities, but it also demonstrated the devastating power of nuclear weapons, which would have lasting implications for international relations.

While the other choices relate to significant historical events, they occurred as part of the subsequent global landscape shaped by World War II. The Cold War began as a consequence of the shifting power dynamics post-1945 but was not a direct outcome of the bombings. NATO was formed in 1949 as a military alliance in response to perceived threats from the Soviet Union, and the United Nations was established in 1945, but it was aimed at preventing future conflicts rather than being a direct result of the bombings. Therefore, the most direct and immediate outcome of the atomic bombings was indeed the end of World War II, influencing the course of history significantly in the years that followed.