70s SciFi Movie with Aliens Seeking 'The Enemy'

by C J
(Mobile Alabama)

I'm searching for a movie that has male and female aliens who come to earth looking for their "enemy". They have glasses that can see the true form of the enemy and at the end the female shoots the male and as she walks off you see here through the glasses and she is one of the enemy.

What is the name and who were the actors?