Triangular formation of lights with fourth light out of formation traveling slowly and quietly.It was a clear calm cool night in central Idaho, when I received a phone call from my nephew who lives about a half mile away. He said there were strange lights outside and that they had been moving around the northern end of the valley from east to west.I went outside while still on the phone with my nephew and he said look to the WNW and we both saw one large lone reddish-blue silver light glistening in the WNW Sky. It appeared to be 3-5 miles away, however I am not certain. He said he and his father had been observing for longer and said more would appear, that they had been visible and then not, just then one light appeared and then several seconds later another appeared then several seconds later a third light appeared. These three lights were in a near perfect triangle, not an isosceles but flatter with approximate 45-degree angles.They remained that way for maybe 30 seconds with all four lights glistening the same sharp reddish-blue silver light. The fourth light appeared closer because of its brightness also it was positioned higher and to the left of the triangular formation of lights. The lights appeared to hover and move very slowly to the left, keeping their same distance from me. The lights forming the triangle then vanished into the westward sky and left the remaining fourth light that slowly drifted to the left and west over the horizon of mountains. No sound was ever heard form these lights.Ten minutes later a large plane came from the ESE and crossed directly over and directly in line with the west ward direction of the lights until out of sight. This plane had a deep roar of motors had no normal colored airline lights, but several large yellowish orange lights marking its body. Not sure if plane was in support of the light formation or in search or niether.Do not know if lights were military training or just what they were. All I know for sure is lights were very unique in appearance and behavior of any thing I have ever witnessed in nearly 50 years of living in this area.