Most of them were discovered in deep hibernation. While others we've - contained at top-secret sites around the world. Cambodia and Mexico, Skull Island. We even found one in Wyoming. They're everywhere.
Killing them would be a mistake. They returned because of us. It was our atomic testing that awoke Gojira. Other creatures like the MUTOs. From strip-mining and seismic surveys. But these are not MONSTERS! They are animals, rising to reclaim a world that was once theirs!