Shortly after the launches, President Yoon Suk-yeol led his first meeting of the National Security Council.
He ordered officials to implement "extended deterrence" with the United States and strengthen the joint defense posture.
Officials there noted that North Korea's missile test was conducted before President Biden had even arrived back in the U.S. from his trip to Northeast Asia.
Meanwhile, South Korea's National Security Adviser Kim Sung-han spoke over the phone with his U.S. counterpart Jake Sullivan and discussed coordinated responses as well as assessments of the recent Yoon-Biden summit.
The South Korean government issued a statement "strongly" condemning North Korea's launches, calling them "unlawful" and a "grave provocation" that threatens peace.
It also urged the North to abide by UN Security Council resolutions and respond to calls for dialogue.