This file photo, provided by the Joint Chiefs of Staff, shows South Korea and the United States holding joint missile drills at an unspecified location last Wednesday. (Joint Chiefs of Staff,)

South Korea lost track of a missile fired during last week's live-fire drills held in response to a North Korean intermediate-range ballistic missile (IRBM) launch, Seoul officials said Thursday, in a failure that raised questions over the missile's performance.

The missile was one of the two Army Tactical Missile System (ATACMS) missiles that the South Korean military fired into the East Sea following the North's IRBM launch on Oct. 4. The US Forces Korea also fired two ATACMS missiles in the combined drills.

The missile went out of contact, meaning it remains unknown whether it hit the intended target. The three other missiles accurately hit mock targets, according to informed sources.

After the drills, South Korea's Joint Chiefs of Staff said the missiles were fired for precision strikes at the targets, and that the allies demonstrated their combined force to deter additional North Korean provocations.

Also in response to the North's IRBM launch, the South Korean military mobilized a Hyunmoo-2C ballistic missile.

But it fell inside a military base after an abnormal flight. Its warhead was found around 1 kilometer back of the launch point and just 700 meters away from the nearest civilian home, a JCS official said, requesting anonymity. (Yonhap)