WASHINGTON, Aug. 11 -- The United States urged Russia and Ukraine to avoid the scalation of tension in Crimea, the State Department said Thursday.

"We are extremely concerned about the increased tension near the administrative boundary between Crimea and Ukraine," Elizabeth Trudeau, spokesperson for the State Department, said at a regular press briefing.

Tensions between Russia and Ukraine have been escalating as Russian President Vladimir Putin on Wednesday accused Kiev of plotting terrorist attacks in Crimea and vowed to take additional measures to ensure the safety of infrastructure and citizens there.

"The people who seized power in Kiev ... have switched to terror tactics instead of searching for ways for a peaceful settlement," Putin told a news conference.

The United States called for the avoidance of any actions that would escalate the situation in Crimea, Trudeau said.

"We believe now is the time to reduce the tensions, reduce the rhetoric and get back to talks," the spokesperson said.

The Russian Federal Security Bureau (FSB) said Wednesday the country has prevented a series of terrorist attacks in Crimea planned by the Ukraine military intelligence service.

Ukrainian National Security and Defense Council Secretary Oleksandr Turchynov said the claims were "hysterical and false," and the Ukrainian Defense Ministry termed the allegations as Moscow's attempt to justify its re-deployment and actions in the region.

Crimea, which was previously part of Ukraine, was incorporated into Russia in 2014 following a referendum, which was recognized by Moscow but rejected by Ukraine and Western powers.

"Our position ... is well known. Crimea is part of Ukraine and it is recognized as such by the international community," Trudeau said.