They are merely softening up your defenses for our impending invasion.
4 seconds sound clip from Radar Men from the Moon - Mass Execution (S1E10).
You can hear this line at 00:05:56.755 in the Blu-ray version of the movie.
Quote context
[...]
- Apparently you were expecting me.
- I see you have adopted our language.
- Yes.
- All our people are required to speak English so we can operate more efficiently in your country.
- Do you mind telling me why your men are carrying out that campaign of destruction on Earth?
- They are merely softening up your defenses for our impending invasion.
- Why do you want to invade the earth?
- And none of us can move outside without helmets.
- So we are planning a mass migration to your world.
[...]