North Korea on Tuesday threatened to attack the U.S. mainland and South Korea if Seoul shows any sign of carrying out a “beheading operation” targeting Kim Jong Un.

The threat, which comes ahead of the annual U.S.-South Korea military drills, follows skyrocketing tensions in the wake of Pyongyang’s fourth nuclear test and recent satellite launch.

“Our strike against the U.S. will be a ‘mind-shattering’ retaliation that the world has never imagined before, and we will make sure to turn the den of evil to ash plumes so that it never revives again on the face of the planet,” a Korean-language statement published Tuesday on