Theresa May will seek the “shoulder to shoulder” support of other EU countries to face the growing threat from Russia, telling their leaders: “We are all at risk.”
The Prime Minister will use a Brussels summit on Thursday to push for a hard-hitting communique to underline the joint belief that the Kremlin was behind the nerve agent attack on double agent Sergei Skripal and his daughter.
EU leaders will not be asked to impose their own sanctions at this stage – although the UK has pushed privately for the expulsion of Russian spies where any are identified in other countries’ embassies.
But Ms May will use the summit to stress that “the Russian threat does not respect borders and, as such, we are all at risk”, a No 10 official told The Independent.
And she will tell fellow leaders: “The challenge of Russia is one that will endure for years to come.
“As a European democracy, the United Kingdom will stand shoulder to shoulder with the European Union and with Nato to face these threats together. United we will succeed.”
The appeal will follow further tensions in relations with Russia, as Moscow’s Ministry of Foreign Affairs claimed Britain had poisoned Mr Skripal.
“Logic suggested” the UK had carried out the attack in Salisbury, claimed Vladimir Yermakov, head of the ministry’s non-proliferation and arms control department.
The only alternative conclusion was that UK authorities were “not able to provide protection from… a terrorist attack on their soil”, he said, at a briefing in the Russian capital.
In Britain, the security services believe they are compiling ever more powerful evidence that Russia was responsible, based on its past behaviour, its motive and the nerve agent used, called Novichok.
Russia has previously produced the chemical, has a record of carrying out state-sponsored assassinations and is known to view defectors as legitimate targets, they say.
Detailed information about the type of Novichok used has been shared with some key UK allies – and efforts are underway to convince the Greek government, thought to be the most sceptical of Russian culpability.
The UK has also compiled a list of 17 different explanations Russia has given for the attack – ranging from suicide, an accidental overdose and a distraction from Brexit, to murder by everyone from Sweden to the daughter’s future mother-in-law.
A senior Whitehall official said it was clear that Russia is a “strategic enemy, not a strategic partner”, but added: “We are not looking for confrontation or regime change.”
This week, Downing Street backed away from further reprisals against Russia – despite the Kremlin going beyond a tit-for-tat expulsion of diplomats by closing the British Council.
However, it said the Government was still “actively considering” other measures and “stand ready to deploy at any time”.
In Brussels, the Prime Minister will address the other 27 leaders over dinner, when she will also make a short speech welcoming progress in the Brexit negotiations.
The EU is poised to sign off the transition deal she is seeking, as well as agree guidelines for the looming talks on a long-term economic and security relationship.
The talks will also focus on jobs, trade and digital taxation, where Ms May will welcome EU proposals which include a new 3 per cent levy on the turnover of tech giants.