South Korean President Moon Jae-in on Saturday ordered his aides to consult with the US about the deployment of four more THAAD mobile launchers after North Korea's launch of a ballistic missile.

North Korea on Friday night test-fired an intercontinental ballistic missile (ICBM) called Hwasong-14 from Jagang province, Xinhua news agency quoted South Korea's Joint Chiefs of Staff (JCS) as saying.

The ballistic missile of an intercontinental range flew about 1,000 km and was lofted as high as around 3,700 km.

It was an advanced Hwasong-14, which travelled 933 km at a maximum altitude of 2,802 km at the July 4 launch.

Right after North Korea's missile launch was reported to Moon, the President convened the national security council (NSC) meeting at the Blue House.

Moon instructed his aides to consult with the US on strengthening South Korea-US defence capability and reliable expanded deterrence capability, including the early installation of the remaining Terminal High Altitude Area Defence launchers, presidential press secretary Yoon Young-chan said.

On April 26, two mobile launchers and other elements of the US missile shield were transported in the middle of night to the former golf course in Seongju county.

One THAAD battery, which Seoul and Washington decided in July last year to deploy in southeast South Korea, is composed of six mobile launchers, 48 interceptors, the AN/TPY-2 radar and the fire and control unit.

Four THAAD mobile launchers were reportedly delivered to a US military base near the THAAD site.

A senior presidential official said additional THAAD launchers would be "temporarily" deployed, saying the "general" environmental impact assessment would be conducted as planned.

The Defence Ministry on Friday announced its plan to conduct the general green audit on the THAAD site that was expected to take 12 months.

The ministry forecast the period could be shortened as a small-size green audit was already completed.

The presidential official said the final decision on whether to deploy the US missile defence system in South Korea would be decided upon around the time when the green audit is completed.

The South Korean President has ordered a show of force through the joint US-South Korea missile-firing drills in response to Pyongyang's missile-launch provocation.

Earlier in the morning, the combined forces of South Korea and the US staged the live-fire missile exercise along the east coast, mobilising the South Korean military's Hyunmoo-II ballistic missiles and eight US Army's ATACMS surface-to-surface missiles.