TOP SECRET Combat Effectiveness 4. The chief threat from the enemy air force comes from the MIG 15 aircraft. From their existing bases these can operate as far south as the 38th parallel. Should the Communists succeed in operating from their bases in the Pyongyang area the MIG 15 could operate effectively as far south as the 36th parallel. Although we have no evidence that Communist jet pilots have been given training in close support operations they could carry out low flying attacks. 5. Up to date the Communist air force has been primarily a defensive force, and as such it has only recently shown signs of being able to impede seriously U.N.