After Ukrainian authorities blocked access to Yandex, a Russia-based Internet company best known for its search engine, and other major Russian social media websites earlier this month, the Security Service of Ukraine (SBU) conducted searches Monday at Kiev and Odesa offices of Yandex which was suspected of treason, reports said.

"Within the framework of the criminal proceedings on high treason, searches are being conducted at the mentioned companies in Kyiv and Odesa," SBU spokesperson Olena Hitlianska told Interfax-Ukraine.

Long before Russia allegedly meddled with the U.S. presidential election last year and then the French election this year, Ukrainian lawmakers had warned of Russian's cyber attacks and interference. The Ukrainian term for Russian cyber attacks is "hybrid warfare," for which the Ukrainian government took action this month, the Washington Times reported.

Read: What Is The Cost  Of Preventing Cyberattacks And Hacks On The Internet?

The motive behind banning Russian social media websites, as told by President Petro Poroshenko, was to stop Russia's annexation of the Crimean peninsula and continuing interference in eastern Ukraine, reports said.

Following a decision by the National Security and Defense Council, Poroshenko banned Russian social media sites and propaganda outlets that were acting as a source of fake news. The move is part of a larger set of sanctions against Russia, which is likely to restore the cyber sovereignty of Ukraine, according to reports.

According to a report on the SBU website, the management of Yandex had collected data on Ukrainian citizens and transferred to Russia. The data included occupation, lifestyle, housing, residence, work, leisure, sources and amounts of income, telephone numbers, email addresses and social network accounts. 

"The information was then passed on to special services of the Russian Federation for planning, organizing and conducting reconnaissance, sabotage, information and subversive operations in our country to harm Ukraine's sovereignty, territorial integrity and inviolability," the website reported.

Some Ukrainian officials described the move of the president to ban Russian social media sites as a national security measure. 

"The servers of these Russian social networks ... store the personal data of Ukrainian users and information on their movements, contacts, communications," Volodymyr Ariev, an MP from President Petro Poroshenko's political faction, said on Facebook.

Russia is known for cyber attacks against foreign countries, which it sometimes does, to help or harm a specific political candidate or sow chaos. The motive behind its attacks are always to project power, according to NBC News.

Starting from 2007, the Russians have attacked former Soviet satellites like Estonia, Georgia, and Ukraine. Russia has also hacked sites of Western nations such as the U.S. and Germany. 

U.S. intelligence officials and cyber experts have argued that a strategy pairing cyber attacks with on-line propaganda was launched by Russian intelligence a decade ago and has since been expanded under Putin, reports said.

Mike McFaul, the former U.S. ambassador to Russia, said: "For years now, the Kremlin has looked for ways to disrupt democracies, to help the people that they like to come to power and to undermine the credibility of the democratic process."

Stefan Meister, who has written extensively on Russian security strategies for the German Council of Foreign Relations, called the attacks, which often include fake news, "a security strategy, not a media strategy."