text: what was the main reason of ussr defeat in afghan war and withdrawal of forces?   the main reason behind the ussr defeat was economic collapse. the us-funded militants in afghanistan (bin laden was one) basically fought until the ussr ran out of money. this led to the collapse of the soviet union and the destruction of the berlin wall.  it seems that bin laden is trying for a repeat performance with the us. he attacked our financial center and has involved us in a "war without end" against terrorism, bleeding the federal reserve dry.