The world has long been familiar with two military challenges posed by the forces of world communism - the challenge of nuclear war and the challenge of large-scale conventional war. The United States and the free world meet these challenges by maintaining the ability to fight both kinds of war-an ability so powerful it has deterred Communists from starting either kind. Today, we are seeing with increasing frequency evidence of another technique the Communists use whenever they consider the occasion appropriate...the technique of unconventional warfare -"The Third Challenge." This challenge involves conspiracy, underground organization and terror. It encourages guerrilla warfare and avoids open conflict and risks by the oblique method of conquering other countries from within. This week's THE BIG PICTURE, narrated by Alexander Scourby, deals with that third challenge and depicts the United States capability to fight this type of war in the far flung reaches of the globe.