WASHINGTON -- The United States imposed new sanctions on the government of North Korea for using a chemical agent to kill Kim Jong-un’s half-brother, US State Department spokesperson Healther Nauert said in a press release.

"The United States determined under the Chemical and Biological Weapons Control and Warfare Elimination Act of 1991 (CBW Act) that the Government of North Korea used the chemical warfare agent VX to assassinate Kim Jong-nam in the Kuala Lumpur airport," Nauert said Tuesday.

The measures, she added, are in addition to existing US comprehensive sanctions targeting unlawful North Korean activities. The sanctions took effect March 5, Nauert said.

VX is a nerve agent, a substance listed by the Chemical Weapons Convention as a chemical weapon and classified by the United Nations as a weapon of mass destruction.

Kim Jong-nam was killed by the chemical at the Kuala Lumpur International Airport on Feb. 13, 2017, travelling by the name of Kim Chol.

Pyongyang has repeatedly denied the accusations of involvement in Kim's poisoning, saying that the reports are part of an aggressive campaign against North Korea's nuclear program. (Sputnik)