What is the most widely accepted theory on how early humans migrated to north america?

What was the impact of the united states involvement in the soviet-afghan war? 1.american involvement established a democratic government in afghanistan that allowed for freedom for its citizens. 2.american involvement led to the first instance of combat between the united states and the soviet union during the cold war. 3. american involvement led to a protracted war for the soviet union that ultimately aided in an economic collapse. 4. american involvement allowed for the mujahideen to carry out terrorist attacks on the kremlin.