North Korea issued a stark warning after the US and South Korea launched their annual joint military drills. Kim Jong Un’s sister, Kim Yo Jong, said the exercises could destabilize the Korean Peninsula and pledged to strengthen the country’s deterrence capabilities.

South Korea and the United States will conduct their annual joint military exercises, Freedom Shield, from March 9 to 19, military officials announced Wednesday. The drills are described as “defensive in nature,” though they have historically drawn criticism from North Korea, which views them as a rehearsal for invasion.

Ulchi Freedom Shield 24, a joint largest ever air combat exercise between South Korea and the United States is going on amid advancing North Korean military threats.