Red lights blinking.

I live on Georgetown Lake in southwestern Montana at an elevation of 6,200 feet.  On the night of Saturday December 9, 2017, at about 8:30 p.m.,  I saw about 15 moving red blinking lights.  They were to the south of where I live about 1,000 feet above the mountains that are over 10,000 feet in elevation.  The mountains are about 15 miles from where I live.  The lights were moving horizontally.  The lights were moving in a northeasterly direction.  I estimate that the row of lights was 10 miles long.  They were evenly spaced and all were at the same elevation.  It looked like they were being towed because they all followed the same path.  The blinking of the lights alternated.  When one light blinked on the light closest to it did not.  Every other light blinked at the same time.  The sighting lasted about 3 minutes.  
I did not have my phone with me so no video.  I did not want to go get it  because I did not want to miss what I was seeing.  It did not seem possible.  There was also no sound.  It is very quiet where I live so if it was plane, I would have heard it.