A South Korean Defense Ministry official said that the United States and South Korea launched eight ground-to-ground missiles in the early hours of Monday off the east coast of South Korea after North Korea launched a barrage of short-range ballistic missiles on Sunday.

South Korea’s Yonhap news agency quoted the South Korean military as saying that this action is proof of the "capability and readiness to carry out a precise strike" against the missile launch source in North Korea or command and support centers.

South Korean President Yoon Suk-yeol, who took office last month, pledged to take a tougher stance against North Korea and agreed with US President Joe Biden at the May summit in Seoul to update joint military exercises and establish mutual deterrence.

The South Korean and US militaries launched eight ground-to-ground missiles over about 10 minutes starting at 4:45 a.m. on Monday in response to the eight missiles North Korea launched on Sunday, Yonhap reported.

A South Korean Defense Ministry official confirmed the launch of eight Army Tactical Missile Systems (ATACMS).

The US Indo-Pacific Command said the exercises involved one US Army missile and seven from South Korea.

It said in a statement, using the initials of South Korea’s official name. North Korea’s short-range ballistic missiles, launched towards the sea off its east coast on Sunday, were likely its largest single test and came a day after South Korea and the United States ended their joint military exercises.

The bilateral exercises included a US aircraft carrier for the first time in more than four years. Japan and the United States also conducted joint military exercises on Sunday in response to North Korea’s latest missile tests.

North Korea criticized the previous joint exercises as an example of Washington’s continued “hostile policies” towards Pyongyang, despite talk of diplomacy.

North Korea has conducted a series of missile launches this year, from hypersonic weapons to tests of its largest intercontinental ballistic missiles (ICBMs) for the first time in nearly five years.

Yonhap, quoting an unidentified source, said the North Korean airstrike was launched on Sunday from four locations, including Sunan in the capital Pyongyang.

North Korea has continued its recent trend of not reporting missile launches in state media, which some analysts say is meant to show that they do so as part of routine military exercises.

Officials in Washington and Seoul have recently also warned that North Korea appeared ready to resume nuclear weapons tests for the first time since 2017.

Last month, North Korea launched three missiles, including one believed to be its largest intercontinental ballistic missile, the Hwasong-17, after Biden ended his trip to Asia where he agreed on new measures to deter the nuclear-armed state.

South Korea-US joint forces also launched missiles in response to those tests, which the allies say are violations of UN Security Council resolutions.

Last month, the United States called for more sanctions on North Korea for its ballistic missile launches, but China and Russia have so far objected to the proposal.