Moscow strongly denies involvement in the attack, and Russian officials said they didn’t recognize the suspects.
Britain plans to press its case against Russia at the U.N. Security Council on Thursday.
The Skripals’ poisoning ignited a diplomatic confrontation in which hundreds of envoys were expelled by both Russia and Western nations. But there is limited appetite among Britain’s European allies for further sanctions against Moscow.
Wallace told the BBC that Britain would “push back the Russian malign activity” with “whatever means we have within the law and our capabilities.”
He said Britain would “challenge the Russians in both the overt and the covert space, within the rule of law and in a sophisticated way.”