The report in particular argues that North Korea has been improving the guidance of the ballistic missiles allowing Pyongyang to hit specific targets, the CNN broadcaster reported on Friday.
Some progress has been reportedly made even during the thaw in the relations between South Korea and North Korea, which was achieved thanks to the Winter Olympics in Pyeongchang.
North Korea has faced several rounds of sanctions over its nuclear and ballistic missile tests, conducted in violation of the UN Security Council resolutions.
On December 22, the UN Security Council unanimously adopted the resolution further tightening sanctions against North Korea over its ballistic missile launch conducted on November 29. The US-drafted resolution caps Pyongyang’s petrol imports and expands the ban on goods exports.