Moscow will take retaliatory action against increased NATO activity near its border, Russia’s top general said Friday, a day after the Western military alliance's security general said there were signs of Russian forces withdrawing from its border with Ukraine.

As Ukraine prepares to hold its presidential elections Sunday, tensions have heightened in the region. After Russia annexed Crimea, NATO suspended all practical cooperation with Russia, while violence between government forces and pro-Russian separatists in eastern Ukraine have worsened over the weeks. On Thursday, clashes claimed the lives of at least eight security personnel near Ukraine’s fifth-largest city, Donetsk, which is controlled by Russian supporters.

"NATO's military groupings in the Baltic states, Poland and Romania are being built up, as well as the military presence of the bloc in the Baltic, Mediterranean and Black Sea," General Valery Gerasimov, the chief of general staff of the Russian armed forces, told a conference in Moscow, according to Reuters. "The intensity, the operational and combat readiness of the (western military) alliance's troops is being increased near the Russian border. In these circumstances ... We have to take retaliatory measures.”

Deputy Defense Minister Anatoly Antonov told Reuters Friday that Russia will “100 percent” withdraw forces deployed to regions near its border with Ukraine "within a few days," adding: “We will leave less than nothing behind.”

NATO Chief Anders Fogh Rasmussen had said on Thursday: “Late yesterday (Wednesday), we have seen limited Russian troop activity in the vicinity of the border with Ukraine that may suggest that some of these forces are preparing to withdraw. It is too early to say what this means, but I hope this is the start of a full and genuine withdrawal.”

However, he added that most of the previously deployed Russian forces are still present near the Ukraine border and continued “Russian exercises” could be seen in the area, and noted that if the forces did withdraw, it would be the “first step from Russia into the right direction of living up to its international commitments.”

"I hope we will see a political and diplomatic solution to the crisis in Ukraine," he said.

Earlier this week, Russian President Vladimir Putin announced that Russia would withdraw its troops, estimated by NATO to number 40,000, from its border with Ukraine. On Wednesday, Putin said that the pullback was meant to create "favorable conditions for Ukraine's presidential vote and end speculation," according to Associated Press.