North Korea launched several missiles Saturday following the conclusion of a U.S.-South Korea joint military exercise.

The hermit kingdom fired a series of cruise missiles around 4:00 a.m. on Saturday — local time — according to the South Korean Joint Chiefs of Staff.

“While strengthening our monitoring and vigilance, our military is maintaining a full readiness posture in close cooperation with the United States,” the JCS said in a text message to the press, according to Yonhap News Agency.

The Ulchi Freedom Shield (UFS) exercise — a joint venture between the militaries of the U.S. and South Korea — concluded on Thursday.

The drills were a source of immense irritation for the North Korean supreme leader Kim Jong Un and the country’s regime, prompting a series of stunts in response. On Wednesday evening, North Korea’s military fired two tactical ballistic missiles from its capital city of Pyongyang to practice “scorched earth strikes” over major South Korean command centers and operational airfields, according to the official Korean Central News Agency.

The North’s military said it observed the missiles detonating at a set altitude, suggesting their simulated strikes included the explosions of dummy nuclear warheads. Atomic weapons, such as those used during World War II over Japan, are typically detonated above the Earth, rather than hitting it directly, to increase their devastating potential.

According to KCNA, Kim Jong Un visited an army post where his military has been holding command post drills in response to the South Korean-U.S. military training. The outlet reported the North rehearsed “occupying the whole territory of the southern half” of the Korean Peninsula.

North Korea’s military failed its second attempt to deploy a satellite in orbit last week, with its rocket failing in the third stage of flight. North Korea’s National Aerospace Development Administration said it will attempt to launch a spy satellite again in October.