South Korean and U.S. troops will begin their large annual joint military drills next week to enhance their readiness against North Korean threats.

At least eight people were hurt on Thursday after a shell was dropped on a civilian district, damaging houses and a church during live-fire military exercises in Pocheon, South Korea, a fire official said.

South Korea, a stable U.S. ally, proved that even economically successful and democratic nations can implode at a moment’s notice. Such instability would only be exacerbated if South Korea were a nuclear weapons state.

North Korea has strongly criticized the United States over what it calls “political and military provocations.” The statement came after the US Navy aircraft carrier USS Carl Vinson docked in the South Korean port city of Busan on March 2.