The 27th Day
I just watched The 27th Day (1957), directed by William Asher.
The screenplay by John Mantley is based on his 1956 novel of the same name.
"People hate because they fear, and they fear what they don't understand, which is almost everything!"
It features Paul Frees as the newscaster! You might not recognize his face, but you'd surely know his voice. He did a squidzillion voices back in the day and is perhaps best known as Burgermeister Meisterburger.
The film recycles footage from Earth vs. The Flying Saucers (1956).