What year did the Cold War officially begin?

The Cold War is generally considered to have officially begun in 1947. This period of geopolitical tension between the Soviet Union and the United States, along with their respective allies, emerged after World War II as the two superpowers sought to expand their influence globally. The term "Cold War" itself was popularized in the late 1940s, particularly after Winston Churchill's famous "Iron Curtain" speech in 1946, which highlighted the division of Europe into Western and Eastern blocs.

The formal start of the Cold War is often marked by the announcement of the Truman Doctrine in March 1947, which committed the United States to countering Soviet expansionism. This was followed by the Marshall Plan later that year, aimed at rebuilding Western European economies to prevent the spread of communism. The ideological, political, and military rivalry that characterized the Cold War would last for several decades, influencing global affairs until the dissolution of the Soviet Union in 1991.