The US-Italy relationship was forged in the crucible of the Second World War. American and Allied forces landed in Sicily in July 1943, beginning a gruelling campaign that liberated the peninsula from fascism and German occupation. The human cost — borne by both Italian civilians and American service members — created a bond that transcended mere strategic calculation. More than 120,000 American soldiers are buried in Italy's military cemeteries, a permanent reminder of the sacrifice that underlies the alliance.
Postwar reconstruction was shaped decisively by the Marshall Plan (European Recovery Program, 1948–1952). Italy received approximately $1.5 billion in American assistance — one of the largest national allocations — helping to stabilise the economy, suppress inflation and fund the industrial investment that would underpin the "economic miracle" of the 1950s and 1960s. The Plan also carried a political dimension: American assistance was consciously deployed to support centrist democratic forces against both the far right and the Italian Communist Party (PCI), then one of the largest in Western Europe.
Italy's decision to join the North Atlantic Treaty at its founding in April 1949 was not foregone. Italy's defeat in the war raised questions about its eligibility; its large communist electorate raised concerns about reliability. Yet the United States pushed for Italian membership, recognising that the peninsula's strategic position — jutting into the central Mediterranean, flanking Yugoslavia, and providing bases for projecting power towards the Middle East and North Africa — was indispensable to NATO's southern flank. Italy was among the twelve founding signatories of the Washington Treaty on 4 April 1949.