U.S. President Donald Trump announced more sanctions against the "brutal" North Korean regime on Thursday.

Two U.S. supersonic B-1 Lancer strategic bombers flew over South Korea on Tuesday morning in a show of force and solidarity with its ally amid heightened tension following North Korea's fifth nuclear test on Friday.

After North Korea's most recent nuclear test last Friday, South Korea's president said North leader Kim Jong Un's "mental state is spiraling out of control" and that his government has "fanatic recklessness."