Giving voice to what everyone is already thinking, British Foreign Secretary Boris Johnson said Friday that Russian President Vladi­mir Putin personally ordered the nerve agent hit on Russian-born ex-British spy Sergei Skripal and his 33-year-old daughter, Yulia in Salisbury. Without mincing words, England’s top diplomat called Putin’s direct involvement “overwhelmingly likely”.

Johnson’s comments followed Prime Minister Theresa May’s decision Wednesday to expel 23 Russian diplomats from Britain. Russia confirmed Friday it will expel British diplomats and halt high-level meetings in turn.

“Our quarrel is with Putin’s Kremlin, and with his decision — and we think it overwhelmingly likely that it was his decision — to direct the use of a nerve agent on the streets of the U.K., on the streets of Europe for the first time since the Second World War,” Johnson said during a visit to a museum in London.

The U.S. along with a coalition of other European nations issued a statement Thursday backing England in their response, calling the use of the nerve agent — the first time on British soil since WWII — “an assault on the United Kingdom’s sovereignty and any such use by a state party is a clear violation of the Chemical Weapons Convention and a breach of international law.” The statement also expressed a belief that the attack was a threat to the security of every member of the coalition, which includes Germany and France.

In an almost immediate response, Kremlin press secretary Dmitry Peskov told state-run Tass news agency that Johnson’s allegation was an “unforgivable breach of diplomatic etiquette”.

“Any reference or mention of our president in this connection is nothing but a shocking and unforgivable violation of the diplomatic rules of propriety,” Peskov said.

Moscow has also suggested, via Foreign Minister Sergei Lavrov, that Britain is behaving in a “boorish” way as regards the poisoning because it is facing challenges related to its decision to leave the European Union.

Lavrov said Russia will respond to the accusations and the move to expel Russian diplomats from England “very soon.”