They could be afraid of us because it only takes 2 keys each in China, Russia, and us to make things burn up.
Some say that our brain produces a chemical when we are fearful which is like a thrilling drug to them.
Others say they like our cow blood, human blood etc.
Others say the planet has other resources they like.
God knows. I think it's something else . . . like trying to sabotage God's plans with this crop of future rulers to rule and reign with Christ or observing their training or . . . God knows . . .