Such a statement, was made in an interview with The Sun Online by Professor Paul Springer from the US Air Force College in Alabama.
At the same time, he compared potential alien invaders with Europeans who came to the New World 300 years ago and actually exterminated the local inhabitants there.
So the aliens, in his opinion, can try to destroy earthlings in order to get the resources available on the planet.
Paul Springer is sure that any civilization acts solely in its own interests, which may not include good will, so you need to prepare for any scenario.
The specialist also explained that the alien invaders may have weapons that are much superior to the earth.
For example, they can use special lasers for pinpoint strikes against ground targets. Or they may have asteroid bombardment technology. Another option for the invaders is to spread viruses that act exclusively on people to cleanse the planet.