North Korea says its leader Kim Jong Un oversaw firing drills designed to simulate a nuclear counterattack on Monday, and it notes the exercise involved the use of "super-large rocket launchers."

On Tuesday, the ruling Workers' Party newspaper Rodong Sinmun published photos of rockets being fired from four mobile launchers. It says the 600 mm rockets hit a target island 352 kilometers away.

The super-large rocket is believed to be a short-range ballistic missile capable of carrying a tactical nuclear warhead.

South Korea's military says the North launched what appeared to be multiple short-range ballistic missiles from a site near Pyongyang on Monday.

North Korea says the firing drills are aimed at countering the joint training sessions that US and South Korean forces are holding at Kunsan Air Base. The facility in southwestern South Korea falls within the claimed range of the North Korean rockets.

Pyongyang also conducted a firing drill involving the super-large rocket launchers in March. After Monday's drill, Kim Jong Un reportedly praised the progress that is being made in the country's effort to build up its tactical nuclear attack capabilities.