The British and Dutch governments have condemned Russia's "reckless" GRU intelligence service after it was accused of launching a cyberattack on the global chemical weapons watchdog investigating the Salisbury nerve agent attack.
A joint statement from Theresa May and Mark Rutte said the spy agency had shown a "disregard for the global values and rules that keep us safe" while Jeremy Hunt, the foreign secretary, warned the Kremlin it faced further sanctions.
Officials in the Netherlands, where the Organisation for the Prohibition of Chemical Weapons (OPCW) is based, said four Russians had been expelled in the wake of the alleged cyberstrike.
GRU officers stopped in the Hague planned to travel onwards to an OPCW-approved laboratory in Speiz, Switzerland, which was testing samples from the Skripals poisoning case.
At the same time, the OPCW was also analysing the substance used in a chemical attack on the Syrian rebel stronghold of Douma.
The men were escorted to the Dutch border and sent back to Moscow.
Among them was an officer accused of conducting "malign activity" targeting Malaysian institutions investigating the downing of flight MH17 by rebels supplied with a Russian missile system in Ukraine.
British intelligence helped thwart the operation, which was launched in April, a month after the Salisbury novichok poisoning.
Details were revealed on Thursday after the UK Government accused the GRU of a wave of other cyberattacks across the globe.
Responding to the announcement, Ms May and Mr Rutte said: "We have, with the operations exposed today, further shone a light on the unacceptable cyber activities of the Russian military intelligence service, the GRU.
"This attempt to access the secure systems of an international organisation working to rid the world of chemical weapons, demonstrates the GRU's disregard for the global values and rules that keep us safe.
"Our action today reinforces the clear message from the international community: we will uphold the rules-based international system and defend international institutions from those that seek to do them harm."
The National Cyber Security Centre (NCSC) said a number of hackers known to have launched attacks were linked to the GRU.
The revelations will further strain relations with Russia after Britain blamed Moscow for the nerve agent attack in Salisbury last March which left one person dead.
The NCSC associated four new attacks with the GRU, on top of previous strikes believed to have been conducted by Russian intelligence.
Among targets of the GRU attacks were the World Anti-Doping Agency (Wada), transport systems in Ukraine and democratic elections, such as the 2016 US presidential race, according to the NCSC.
Jeremy Hunt, the foreign secretary, threatened Russia with further sanctions and accused the Kremlin of trying to "fester instability around the world".
He said the latest allegations against the GRU regarding a cyberattack on the OPCW would "put to rest any doubts" about Russia's involvement in the Salisbury poisoning. "Why would you do that if you weren’t the guilty party?" he said.
Asked about Russian meddling in the Brexit vote, Mr Hunt told the BBC he had seen no evidence to support that theory but the UK would continue to monitor the situation.
Jens Stoltenberg, Nato's secretary general, called on Moscow to "stop its reckless pattern of behaviour, including the use of force against its neighbours, attempted interference in election processes, and widespread disinformation campaigns".
The NCSC said it was "almost certainly" the GRU behind a "BadRabbit" attack in October 2017 that caused disruption to the Kyiv metro, Odessa airport and Russia's central bank.
And Britain's cybersecurity chiefs say they have "high confidence" Russian intelligence was responsible for a strike on Wada in August 2017.
The NCSC also stated that the GRU was "almost certainly" to blame for hacking the Democratic National Committee during the US presidential election in 2016.
And the agency pointed the finger at the GRU for accessing email accounts at a small UK-based TV station in 2015.
Delivering a statement on behalf of foreign office minister Alan Duncan, the UK Ambassador to the Netherlands, Peter Wilson, said Russia had "sent officers around the world to conduct brazen close access cyber operations".
He added: "The GRU is an aggressive, well-funded, official body of the Russian State. It can no longer be allowed to act aggressively across the world, and against vital international organisations, with apparent impunity.
"Through our institutions, including the EU, we will work with allies to update sanctions regimes to deter and respond to the use of chemical weapons, we will combat hostile activity in cyberspace, and we will punish human rights abuse.
"The GRU can only succeed in the shadows. We all agree that where we see their malign activity, we must expose it together. And we will."
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