Boris Johnson labelled Russia's counter-measures "futile" as the diplomatic row over the nerve agent attack on a Russian ex-spy rumbled on.
The Foreign Secretary said the Kremlin's tit-for-tat expulsion of 23 British diplomats and the closures of the British consulate in St Petersburg and the British Council would only impact Vladimir Putin's compatriots.
Russia's ambassador to the UK warned the dispute was escalating "dangerously and out of proportion" and the country reserved the right to take "further retaliatory measures" if more sanctions are implemented.
Writing in the Sun on Sunday two weeks after the March 4 incident, Mr Johnson said of Saturday's expulsions: "These futile measures will only punish ordinary Russians by depriving them of harmless opportunities to learn English and apply for UK visas.
"Today Russia stands alone and isolated.
"That fact demonstrates the most telling difference between Britain and Putin: we have friends across the world and he does not."
He said the reaction across the Government, Parliament and the wider country had been "hugely encouraging" but he hit out at Labour leader Jeremy Corbyn, who came under fire on Wednesday after failing to offer explicit support for the Prime Minister's approach in the House of Commons.
Mr Johnson said: "He let down his party and country by seemingly aiding the efforts of the Russian propaganda machine by casting doubt over what is obvious to any objective onlooker."
Theresa May earlier said Britain and its allies would consider their next move and that the national security council would meet early next week.
In an interview with the Mail on Sunday, Russian ambassador Alexander Yakovenko accused Mrs May of using the crisis to improve her image at the expense of relations with Moscow.
"In case of further unfriendly actions against Russia, the Russian side reserves the right to take further retaliatory measures - this is what the British Ambassador was told on Saturday," he said.
Mr Yakovenko called for restraint and "cooler heads", telling the paper: "This dispute is indeed escalating dangerously and out of proportion."
Former double agent Sergei Skripal, 66, and his daughter Yulia, 33, remain in a critical condition in hospital, while Detective Sergeant Nick Bailey, who was exposed to the Novichok nerve agent while responding to the incident, is no longer considered critical.
Russia's ambassador to the EU, Vladimir Chizhov, prompted a strong rebuttal when he suggested the poison may have come from the Porton Down laboratory, which is around eight miles from Salisbury.
He told the BBC's Andrew Marr Show that Russia had "nothing to do" with the incident, however his comments were rejected as "nonsense" by UK officials.
Early on Saturday, Russia's Ministry of Foreign Affairs announced it had ordered the British diplomats to leave within a week and indicated it could take further action should there be what it called more "unfriendly" moves.
Speaking at the Conservative Spring Forum, Mrs May said the Government had "anticipated" a similar response to her action earlier this week to expel 23 Russian diplomats from London.
She said: "But Russia's response doesn't change the facts of the matter - the attempted assassination of two people on British soil for which there is no alternative conclusion other than that the Russian state was culpable.
"It is Russia that is in flagrant breach of international law and the Chemical Weapons Convention."
Meanwhile, counter-terrorism police renewed their appeal for sightings of Mr Skripal's burgundy BMW 320D saloon car, registration HD09 WAO, in Salisbury on the morning of Sunday, March 4.
Metropolitan Police Assistant Commissioner Neil Basu said: "We are learning more about Sergei and Yulia's movements but we need to be clearer around their exact movements on the morning of the incident."