The Trump administration will impose more sanctions on Russia under a chemical and biological warfare law following the poisoning of a former Russian agent and his daughter in the UK earlier this year, the State Department announced Wednesday.

In a statement on Wednesday, State Department spokeswoman Heather Nauert said the U.S. had made this decision on Monday, and accused Russia of violating international law. The statement anticipated the sanctions would go into effect around August 22 in line with the Chemical and Biological Weapons Control and Warfare Elimination Act of 1991, CNN said.

Sergei Skripal, a former Russian spy, and his daughter Yulia Skripal were hospitalized and treated for a nerve-agent attack in March. Yulia Skripal was discharged from the hospital in April, and her father was discharged in May.

Read alsoSkripal Novichok poisoning suspects 'identified' – media

The State Department notified Congress on Wednesday of the first of two potential tranches of sanctions required under the 1991 law. Unless Russia takes certain steps, a second set of penalties –more stringent than this first round – must follow, according to the law.

The first set of sanctions targets certain items the U.S. exports to Russia that could have military uses – so-called dual use technologies. These are sensitive goods that normally would go through a case-by-case review before they are exported. With these sanctions, the exports will be presumptively denied.

A senior State Department official said there would be carve-outs however.

The U.S. would then require Russia to assure over the next 90 days that it is no longer using chemical or biological weapons and will not do so in the future. Additionally, the criteria in the law call for Russia to allow on-site inspectors to ensure compliance.

The official said that if Russia did not meet the demands, the U.S. "will have to consider whether to impose a second tranche of sanctions as specified by the statute."

A former Defense Department official, Mark Simakovsky, said a second tranche would target Russian exports to the U.S. and theoretically could include flights by the state airline Aeroflot as well as a downgrade of diplomatic relations. Simakovsky said he was highly skeptical a second round would be applied. That said, he added, "I don't think this is the last shoe to drop" because of political pressure, criticism from Democrats and the looming midterm elections.