North Korean leader Kim Jong-un visits the Sohae Satellite Launching Ground in Tongchang-ri, North Korea in this undated photo provided by the North Korean government, March 11. AP-Yonhap

South Korea and the United States have detected signs that North Korea is preparing to conduct another intercontinental ballistic missile (ICBM) system test as early as this week, informed sources here said Monday.

Such indications emerged after Seoul and Washington accused Pyongyang, Friday, of having tested a new ICBM system Feb. 27 and March 5 ahead of a full-range ICBM test.

The North has characterized the two launches as "reconnaissance satellite" development tests. South Korean and U.S. officials believe they involved the Hwasong-17 ICBM unveiled during a military parade in October 2020.

"Though we can't say definitively when a missile will be launched, we have been keeping close tabs on the possibility," a government source told Yonhap News Agency on condition of anonymity.

Weather conditions and other variables are expected to affect the timing of the North's possible launch.

Should the North press ahead with a new launch, the North could fire a missile from a transporter erector launcher (TEL) at the Sunan Airport, the site of the two previous tests, observers said.

In the earlier tests, the North fired the missile at a high angle from the airfield and programmed it to travel on the trajectory of a medium-range ballistic missile.

The missile fired Feb. 27 flew about 300 kilometers with a maximum altitude of 620 km, while the one launched March 5 traveled around 270 km at a top altitude of 560 km.

Concerns have persisted that the North could engage in more provocative acts as it made a veiled threat in January to lift its years-long self-imposed moratorium on nuclear weapons and ICBM tests. (Yonhap)