 The North Korean attack surprised everyone. We responded by pushing a resolution through the UN Security Council for military assistance to South Korea. Russia wasn't present to veto this action, as it was then boycotting the Security Council, which is why the UN actually did something useful. President Truman rapidly dispatched our forces to engage in what he called a police action. U.S. and South Korean forces marched into North Korea. This led to Chinese forces entering the war in 1950.