He implemented the so-called “Marshall Plan” aimed at rebuilding the West European economy and instituted NATO doctrine (mutual aid and military defence against an attack by the USSR and its satellite states). Shortly after taking office, he allowed the first and only use of nuclear weapons during the war with an attack on the cities of Hiroshima and Nagasaki, thus leading to the immediate capitulation of Japan. When North Korea invaded South Korea in 1950, he obtained UN consent to the intervention in the so-called Korean War. Truman successfully expanded the US economy after the Second World War and entrenched the superpower position of the US throughout the world. In 1948, he proposed a civil rights act and issued an order commencing racial integration in military and federal agencies.