North Korea often test-fires MLRs during military drills, and in recent years has also developed larger versions of such rockets. Smaller rockets and missiles are seen as central to North Korea's plans for striking targets in South Korea in the event of a conflict.
This year North Korea has test-fired a range of missiles, including from its largest intercontinental ballistic missile (ICBM) to its small MLRs. All are banned under UN Security Council resolutions that have imposed sanctions on North Korea's missile development.
South Korea is pursuing a $2.6-billion artillery interception system, similar to Israel's "Iron Dome", designed to protect against North Korea's arsenal of long-range guns and rockets.
A large part of the area surrounding Seoul, the capital, is home to about half the population of 52 million, and is within range of North Korea’s long-range guns and multiple rocket launchers.
The United States stations around 28,500 troops in South Korea, where they train alongside South Korean troops to counter the North. The allies have conducted missile drills of their own in response to some of North Korea's previous launches.