Russia is facing another round of U.S. sanctions over the poisoning of an ex-Russian spy and his daughter in Britain.

The Trump administration informed Congress on Tuesday that Russia failed to prove it is abiding by a global treaty outlawing biological and chemical weapons.

The U.S. imposed sanctions on Russia in August. A 1991 U.S. law automatically triggers another round of sanctions.

It is unclear what those new sanctions would be or when they would come into effect, angering the chair of the House Foreign Affairs Committee, Republican Ed Royce.

“It is unacceptable that the administration lacks a plan, or even a timeline, for action on the second round of mandatory sanctions,” Royce said Tuesday. “No one should be surprised that Vladimir Putin refuses to swear off future use of weapons-grade nerve agents.”

Former Russian spy Sergei Skripal and his daughter, Yulia, were seriously injured in March when they came in contact with a Soviet-era nerve agent, Novichok, in the British city of Salisbury.

Britain has accused two alleged Russian military intelligence agents of attempted murder.

A woman died and her boyfriend was injured when they apparently came in accidental contact with the poison in June.

Russia has denied any involvement in either case.