North Korea has threatened an immediate military strike against South Korea in response to any “provocation”. Kim Yo Jong, the powerful sister and key ally of leader Kim Jong Un, made the threat on Sunday, as Pyongyang reportedly fired artillery shells near its border with South Korea for the third day in a row.

The remarks follow South Korean military reports that said the North had fired more than 60 artillery rounds on Saturday near their disputed maritime border. A similar volley of more than 200 rounds was reported the previous day.

North Korea fired more than 90 rounds on Sunday, according to the South. “The North Korean military has been conducting the drills north of the South Korean front-line island of Yeonpyeong since about 4 pm,” the South Korean Yonhap news agency reported, citing a military source. Kim Yo Jong said in a statement carried by state news agency KCNA that the safety catch on the trigger of the Korean People’s Army had already been slipped. “As already declared, the KPA will launch an immediate military strike if the enemy makes even a slight provocation, Kim said.