In an interview last week, President Trump called Kim Jong Un a "smart guy" and said he would reach out to the North Korean leader.

The missile launch came on the heels of the newly inaugurated US president acknowledging Kim Jong-un’s hermit state as a nuclear power.

South Korea 's Yonhap News Agency said North Korea might be using a vertical cold-launch system to fire the missiles. The system, which is commonly associated with submarine- and ship-based weapons, ejects a missile from its container before the missile ignites midair.