I was flying from st. louis to newark nj at about 36,000 feet on feb 8th 2017 at about 8 pm somewhere in between st louis and newark nj.I was looking out into the sky as the aircraft was flying ne toward nj. as i looked forward toward the front of the aircraft i noticed a flashing white light just like you see on the plains flying in the sky. but this one did not have a red flashing light as all the aircrafts do. as i kept watching this craft i noticed the flashing light was moving up and down left and right with great agility at about or above 36,000 feet like no other aircraft i've seen. it took me about a minute of watching this before i pulled out my iphone and i captured the flashing light for over ten minutes. let me tell that i have never seeing any aircraft that can do this ever in my life and i've been to 63 countries. this craft was maybe about 500 or so miles in front of my flight so for me to see it the size that i captured on film it must have been a very massive size for it to appear the size of a pill.