NATO Secretary-General Jens Stoltenberg warned Friday that Russia would face ramifications if attempted to invade Ukraine, amid a worrying buildup of forces along the border between the two countries.
"If Russia uses force against Ukraine that will have costs, that would have consequences," Stoltenberg said, per The Associated Press.
"This is the second time this year that Russia has amassed a large and unusual concentration of forces in the region," he added.
"This military buildup is unprovoked and unexplained. It raises tensions and it risks miscalculations," Stoltenberg said, noting that "there is no certainty about the intentions of Russia" but recognizing "this is a military buildup by a country that has invaded Ukraine before."
NATO is set to have a meeting with foreign ministers from its 30 member nations in Latvia from Nov. 30 to Dec. 1, with Russia's recent actions at the top of the agenda.
Ukrainian President Volodymyr Zelensky on Friday said he had received intelligence indicating that a coup was set to take place in his country.
The Russian government has denied any involvement.
On Friday, U.S. national security adviser Jake Sullivan spoke with Ukraine's Head of Presidential Administration Andriy Yermak, according to a statement from the White House's National Security Council (NSC).
"They discussed their shared concerns about ongoing Russian military activities near Ukraine's border and its harsh rhetoric towards Ukraine. They agreed that all sides should pursue diplomatic efforts to de-escalate tensions," NSC spokesperson Emily Horne said in the statement about the call, adding that the U.S. was committed "to Ukraine's sovereignty and territorial integrity."
Both Russia and Ukraine have conducted military exercises this week with Russia reportedly having fighter planes and ships practice airstrikes and Ukraine having military drills.