The United States on Monday imposed new sanctions on North Korea for its alleged use of chemical weapons, a move that follows the suspected nerve agent assassination of the North Korean leader's half-brother.

U.S. Secretary of State Rex Tillerson determined on Feb. 22 that the North Korean regime has "used chemical weapons in violation of international law or lethal chemical weapons against its own nationals," the State Department said in a notice published in the Federal Register.

It did not elaborate, but the North is suspected of masterminding the killing of leader Kim Jong-un's half-brother, Jong-nam, in a VX nerve agent attack at a Malaysian airport in February last year.

The sanctions include a termination of aid to the North, except for urgent humanitarian needs, a termination of arms sales to the regime, and a denial of any credit or other financial assistance.

The new measures are unlikely to have a major impact as Pyongyang is already under heavy international sanctions for its nuclear weapons and ballistic missile programs.

But the announcement could serve to underscore the Donald Trump administration's resolve to keep pressure on the regime until it denuclearizes.

The sanctions will be in place for at least one year and until further notice.

Last week the New York Times reported that the North has supplied Syria with materials that can be used to produce chemical weapons. Pyongyang denied the accusation. (Yonhap)