scorched-earth policy

noun2

1. •
   A strategy that involves destroying buildings, crops, and other resources that could be useful to opponents.

   • The Ethiopian Army waged a scorched-earth policy with saturation bombings and destruction of Eritrea's infrastructure. — 1993
2. •
   (figurative) An intentional course of action that is drastic or ruinous.

   • The scorched-earth policy that voters adopted toward the Tories left them with no seats in Scotland and Wales and greatly reduced numbers through the prosperous swath called Middle England. — 1997