According to Ratas, Estonia unequivocally condemns the nerve gas attack that took place in Salisbury on March 4. "This is a flagrant violation of international law and order," he stressed.

"I already previously canceled a proposed visit to Russia in May, where I would have taken part in Estonian centennial celebrations," said the prime minister. "We must thoroughly discuss further decisions, and we will have a clearer picture in this regard by the beginning of next week. One potential extra step may be the expulsion of Russian diplomats from the country. Naturally we are in close contact with the U.K., and we hope that Moscow is likewise cooperating fully with London."

Minister of Foreign Affairs Sven Mikser (SDE) told ERR's radio news on Friady afternoon that Estonia will announce its countermeasures on Monday.

The Ministry of Foreign Affairs is also to submit a proposal to the Estonian government to impose entry restrictions on 49 individuals included on the so-called Magnitsky List.

EU leaders on Friday unanimously agreed with the U.K. that it is "highly likely" that Russia was behind the nerve agent attack on ex-Russian spy Sergei Skripal and his daughter Yulia in Salisbury. They likewise promised British Prime Minister Theresa May comprehensive support in the investigation into the attack as well as to coordinate further activities.

Tsahkna: Estonia needs to expel Russian intelligence agents

"Russia's attack against the U.K. in Salisbury is an attack against all of us," National Defence Committee of the Riigikogu member Margus Tsahkna told BNS. "This is the message we must relay to the British Secretary of Defence visiting his troops in Estonia on Sunday. The least we can do is support our ally unconditionally and expel Russian intelligence diplomats from Estonia."

According to Tsahkna, Lithuanian President Dalia Grybauskaitė on Thursday said that Lithuania is deliberating expelling Russian diplomats from the country just as the U.K. is doing.

"There is nothing to be discussed at length here by the Estonian government — a clear decision must be made that, similarly to the British, we are likewise expelling Russian intelligence workers working under diplomatic cover," said the Estonian MP.

He added that what would be an especially powerful display of solidarity would be if every EU member state followed suit, but found it would be realistic for at least the Baltic countries and Poland to take this step, noting that the U.K. is a close ally of Estonia.

"When the decision was made at the NATO Warsaw summit in 2016 that allied forces would be sent to the Baltic countries and Poland to deter an aggressive Russia, it was a historic step; before then, NATO's Article 5 had been backed first and foremost by political rhetoric and symbolic flag units," Tsahkna recalled. "NATO also enacted this decision quickly. Today, British troops are protecting Estonia from a possible attack by Russia."

According to the MP, Brexit has strengthened Estonia's defense policy ties, as the British are now even more motivated to actively demonstrate themselves as leaders of Europe's defense capability. "And their troops are in Estonia," he added. "I won't rule out that the U.K. is considering increasing its military presence in Estonia, and the decision to expel spies would demonstrate our concrete support of our allies."

Tsahkna also highlighted that French President Emmanuel Macron has already announced that France is planning to deploy their unit to Estonia again, where it served last year as part of the multinational NATO battle group stationed at Tapa Army Base.

"This is great news," he said, noting that the Estonian government this week also approved the deployment of a unit of up to 50 troops to Mali to serve the French-led Operation Barkhane. "The government should be praised for that," he said, adding that Denmark is also seriously considering continuing the mission.