TOKYO, September 11. /TASS/. THE DPRK has sharply improved the specifications of its missiles since 2019 by shifting to solid fuel and making them harder to intercept, the Nikkei newspaper reported on Sunday.

The shift to solid fuel is one of the main achievements as it complicates satellite surveillance, according to the report. Liquid fuel tanks take longer to fill, allowing satellites to detect preparations for launch. Also, liquid fuel missiles can’t be stored ready for launch for a long time once their tanks are filled.

Solid fuel missiles can be launched unexpectedly, the report said.

An analysis of DPRK’s missile launches showed solid fuel missiles made up 13% of them in 2016-2017, while that proportion climbed to more than 70% after. Pyongyang is now using the new models KN-23 and KN-24 that are similar to ones that are in use by the US and Russia.

In addition, the DPRK has developed technology that allows missiles to maneuver during flight, which makes them harder to intercept. Before 2017 all missiles flew a parabolic trajectory, but 40% of them followed a more complex trajectory after 2019, changing altitude during flight, and sometimes maneuvering left or right.

In the first half of this year, the DPRK launched at least 28 missiles, a new high for six months, which beats the previous record of 25 launches set in 2019. Some estimates suggest the DPRK spent about 2% of its GDP on launches so far this year.

Analysts said have the DPRK is developing tactical nuclear weapons. According to the United States, Japan and South Korea, Pyongyang may conduct a seventh nuclear test as part of the development process.