Col. Halt ... said that it went back and forth. Yeah, as he went north or south in the woods, the lights from the lighthouse and lightship located to the east seemed to move parallel along with them. Have you ever watched the moon through the woods from a moving car?
That's not the motion or sighting described. And humans, though error-prone, DO process information when repeatedly exposed to it (like a recurring lighthouse beam), and compare it to their experiences in order to identify phenomena and decide how to react to it. Especially soldiers stationed in the area, charged with base security during the Cold War.
I guess the radar signals were the lighthouse hovering over the base, too.