NK News on 2nd March reported that the US has said that the North Korean government had used chemical weapons (on its own people) in violation of international laws in a notice posted on the US Government’s Federal Register –
The notice was posted by the State Department’s Bureau of International Security and Nonproliferation, though it did not give further details on how Washington had arrived at the conclusion. The notice also outlined 5 sanctions which would typically accompany such an announcement, including cutting foreign and financial aid, ending military support and export restrictions on sensitive goods – although severe sanctions are already in place
https://www.nknews.org/2018/03/state-department-says-n-korea-has-used-chemical-weapons/