“The decision of President Barack Obama to implement measures against Russia in answer to Russia's cyber meddling is notable for several reasons,” Kaljurand wrote in her blog.

“This is the first time that one country accuses another of cyber attacks, and uses real, public, and extensive countermeasures against cyber attacks organized, supported, ordered, or financed by that country,” Kaljurand wrote. She added that Estonia did the same in 2007, but that the scale of this year’s attacks was different.

“The U.S. countermeasures were expected, because already before the presidential election the U.S. had blamed specifically Russia for hacking and disclosing the emails of the campaign team of Hillary Clinton with the goal of influencing the U.S. presidential election. President Obama also confirmed in his statement today that they have approached the Russians both formally and informally,” Kaljurand wrote.

According to Kaljurand, IT experts believe that it is usually not hard to identify who is behind a cyber attack.

“The political side of an accusation is more complicated — whether and in what way naming a culprit impacts the relationship between countries,” Kaljurand wrote. She added that once accusations were made, appropriate countermeasures had to follow. “This time the U.S. decided to take a political step. It named the culprit, disclosed some of its countermeasures, and reserved itself the right to implement additional countermeasures.”

According to Kaljurand, president Obama had to take into account that countermeasures should be implemented as soon as possible, as the next president of the U.S., Donald Trump, who will be inaugurated on Jan. 20, had said that he planned to reassess the United States’ relationship with Russia as well as the sanctions implemented against the country. The president-elect also said that he did not believe that Russia was behind the cyber attacks.

Even if Trump should change or overturn the countermeasures of the U.S., by that time 35 Russian diplomats would have been sent out of the country, and the technical information would have been published, Kaljurand wrote.

Kaljurand recalled that the most effective countermeasure following the 2007 cyber attacks against Estonia had been adding the names of its organizers in the so-called black list that does not allow them to enter Estonia or the whole Schengen Area.

In a presidential executive order, U.S. President Barack Obama on Thursday enacted sanctions against Russian officials and intelligence services in connection with Russian interference in the U.S. election.

According to Kaljurand, Russia will react and take its own countermeasures against the steps of the U.S. Doing otherwise would be an admission of guilt in the eyes of the Russians, and that it wouldn’t allow, Kaljurand wrote.