South Korea, US launch four missiles in response to North Korea's ballistic missile fire VIDEO

South Korea and the United States fired four ground-to-ground missiles into the East Sea on October 5 in joint drills, a day after North Korea's intermediate-range ballistic missile (IRBM) launch.

The two sides each launched two Army Tactical Missile System (ATACMS) missiles, which precisely hit mock targets and demonstrated the allies' deterrence capability, the Joint Chiefs of Staff (JCS) said, according to the Yonhap news agency.

On October 4, the North fired an IRBM from Mupyong-ri in its northern province of Jagang in its first launch of an IRBM in eight months. It flew around 4,600 kilometres over Japan and landed in the Pacific.

The allies are maintaining a full readiness amid the possibility of additional provocations by the North, the JCS said in a press release without specifying the exact location and time of the drills. Residents in and around the eastern coastal city of Gangneung said they saw a bright flash and heard a strong roar apparently from the training.

The South's military, meanwhile, fired one Hyunmoo-2 ballistic missile, but it fell within the base after an abnormal flight.

It said there have been no casualties reported as it is looking into the exact cause of the incident.

The propellant was burned, while the warhead itself did not explode, a military official requesting anonymity said, adding that it is "very regrettable" that local residents were surprised by that.

Later Wednesday (October 5), the top military officers of South Korea and the U.S. held phone consultations on ways to respond to evolving nuclear and missile threats from the North.

JCS Chairman Gen. Kim Seung-kyum and his U.S. counterpart, Gen. Mark A. Milley, condemned the North's IRBM launch and warned that the North would face a stronger combat posture from the allies if it continued its provocations, Kim's office said.

South Korea and the US held a joint air training on October 4, in which a South Korean F-15K fighter fired two Joint Direct Attack Munition (JDAM) precision bombs at a firing range on a Yellow Sea island.