We (the USA) never attacked nor set foot on North Vietnamese soil. Had we done that, it would have been over in a heartbeat. But our great leader, President Lyndon Bains Johnson, was afraid of initiating nuclear war with the Russians, and he would never allow a US invasion of the North.
P.S. A couple of decades earlier, we invaded North Korea during the Korean war, turning a near certain Communist victory into the stalemate that the Korean war remains in today.
