Explainer: How events have unfolded since the Salisbury nerve agent attack
The diplomatic stakes of Britain's showdown with Russia continue to rise as dozens of officials from both sides face expulsion and accusations continue to mount.
Here, Independent.ie looks at how the aftermath of the attack in Salisbury unfolded.
- March 4 2018:
Former Russian spy Sergei Skripal and his daughter Yulia are found unconscious on a park bench in Salisbury. Their identities are not yet made public.
- March 5:
Mr Skripal and his daughter are publicly identified and declared "critically ill" in hospital.
- March 6:
Politicians and media begin to speculate about Russian involvement in the incident and counter-terrorism officers take over the investigation. The Russian embassy issues two statements accusing the media and Government of "anti-Russian" sentiment.
- March 7:
Police say a nerve agent was used to poison Mr Skripal and his daughter, and the case is being treated as attempted murder.
- March 8:
Home Secretary Amber Rudd says a police officer, one of the first responders to the incident in Salisbury, is seriously ill in hospital.
Politicians continue to speculate on Russian involvement but Prime Minister Theresa May stresses the need to give police the "time and space" to investigate.
Police say 21 people received treatment following the incident.
- March 9:
More than 100 troops are deployed to Salisbury to help with the investigation and clean-up.
- March 12:
Mrs May tells the House of Commons that the nerve agent is of Russian origin and the Government has concluded it is "highly likely" that Russia is responsible for the poisoning. She gives the Russian government until midnight the following day to explain how the nerve agent came to be used in the UK.
White House press secretary Sarah Huckabee Sanders says "the use of a highly lethal nerve agent against UK citizens on UK soil is an outrage".
"We stand by our closest ally and the special relationship that we have," she adds.
Downing Street issues a statement saying Theresa May spoke to French President Emmanuel Macron, who condemned the attack and offered his support.
US Secretary of State Rex Tillerson issues a statement saying he has "full confidence in the UK's investigation and its assessment that Russia was likely responsible for the nerve agent attack".
- March 13:
US President Donald Trump sacks Rex Tillerson in a tweet.
Later, Mr Trump tells reporters outside the White House he plans to speak to Theresa May later that day, adding "as soon as we get the facts straight, if we agree with them, we will condemn Russia or whoever it may be".
The Russian embassy in the UK says Moscow "will not respond to London's ultimatum".
German Chancellor Angela Merkel tells the Prime Minister she stands in "full solidarity" with the UK.
In a phone call with Theresa May, Mr Trump agreed the Russian government "must provide unambiguous answers as to how this nerve agent came to be used", adding that the US "is with the UK all the way".
It emerges that a total of 38 people received medical treated in the aftermath of the nerve agent attack.
- March 14:
The UK is to expel 23 Russian diplomats in retaliation for the nerve gas attack in Salisbury, Theresa May tells MPs. She calls the incident an "unlawful use of force by the Russian state against the UK". The Russian embassy said the expulsion was "unacceptable, unjustified and shortsighted".
Britain asks the international chemical weapons watchdog the Organisation for the Prohibition of Chemical Weapons (OPCW) to verify its findings that Moscow is behind the nerve agent attack.
France provokes alarm by appearing to suggest it did not fully accept the UK's assessment that Russia was responsible for the attack.
President Macron's spokesman suggests Mrs May's response could be considered "fantasy politics".
- March 15:
France seeks to allay concerns by publicly backing the UK's conclusion of Russian involvement, expressed through a telephone call between Mr Macron and Mrs May.
Leaders of Britain, the US, Germany and France issue a joint statement blaming Russia for the Salisbury poison attack. The four allies urge Moscow to provide "full and complete disclosure" of its Novichok nerve agent programme to the OPCW.
Mrs May visits the scene of the nerve agent attack on Mr Skripal and his daughter in Salisbury.
Defence secretary Gavin Williamson strikes a combative note on the incident during a speech in Bristol, declaring Russia should "go away and shut up".
Jeremy Corbyn, meanwhile, urges calm amid the heightened air of suspicion but says the evidence currently "points towards Russia".
- March 16:
Foreign Secretary Boris Johnson says it is "overwhelmingly likely" that Vladimir Putin ordered the use of a nerve agent in the attack on Sergei Skripal.
Calls are made by Labour MP Stephen Kinnock for Russia to be stripped of the 2018 football World Cup.
Russia's foreign minister offers a stinging rebuke to Mr Williamson's comment the day before, suggesting he "lacks education".
Scotland Yard said it was launching a murder investigation after another enemy of President Putin, Nikolai Glushkov, was found to have died from "compression to the neck" at his home in New Malden, south-west London on March 12. The force stressed that no links to the Skripal case had yet been identified.
- March 17:
Russia launches an anticipated retaliation to Mrs May - expelling 23 UK diplomats and shutting down the British Council and British consulate in St Petersburg.
- March 18:
Boris Johnson continues the war of words against the Kremlin, alleging it had been stockpiling the nerve agent Novichok for a decade.
The Foreign Office announces that investigators from the Organisation for the OPCW will visit the UK to take samples of Novichok on March 19. Results are expected within a fortnight.