Dec. 26 (UPI) -- The United States is imposing new North Korea sanctions that target top officials responsible for missile development.
The U.S. Treasury said in a statement Tuesday the two officials, Kim Jong Sik and Ri Pyong Chol, are being singled out for pushing forward with producing weapons of mass destruction.
"Treasury is targeting leaders of North Korea's ballistic missile programs, as part of our maximum pressure campaign to isolate the DPRK and achieve a fully denuclearized Korean Peninsula," Treasury Secretary Steven Mnuchin said in the statement.
Kim played a crucial role in switching North Korea's programs from liquid to solid fuel, a move that could enable the regime to launch missiles with less warning, according to CNBC.
Ri, a former air force general, has been responsible for developing North Korean missiles.
North Korea tested a record number of ballistic missiles in 2017, a trend that is the source of concern in the United States, South Korea and Japan.
Chang Young-keun, a South Korean analyst with Korea Aerospace University, said the developments are taking place at an unexpected speed, local news site Sisa IN reported Tuesday.
Chang said North Korea's use of a gimbal system, that permits each engine to be placed at specific angles, shows new mastery, according to the report.
The Hwasong-15 is also a longer missile than the Hwasong-14, and was launched from a nine-axis self-propelled launching vehicle in November.
The nine-axis vehicle, however, reduces North Korean mobility, according to Chang.
North Korea's missiles have become suddenly successful because of its purchases of advanced Russian-designed RD-250 rocket engines on the black market, as analyst Michael Elleman pointed out in August.
The acquisition of those engines may have been accompanied by a North Korea focus on Ukraine, and alleged attempts to steal missile secrets from a Ukrainian facility.