WASHINGTON — President Joe Biden and Russia’s Vladimir Putin squared off Tuesday over the massive buildup of Russian troops near the Ukrainian border, the U.S. president eager to use his video call with Putin to serve notice that Moscow will face economy-jarring sanctions if it invades neighboring Ukraine.

Just hours before the call got underway, Ukrainian officials charged Russia was continuing to escalate the crisis by sending tanks and snipers to war-torn eastern Ukraine to “provoke return fire.” Ukraine’s Defense Ministry alleged that Russia is holding “training camps under the leadership of regular servicemen of the Russian Armed Forces.” The Kremlin hasn’t commented on the allegations.

Biden aimed to make clear that his administration stands ready to take actions against the Kremlin that would exact “a very real cost” on the Russian economy, according to White House officials. Putin, for his part, was expected to demand guarantees from Biden that the NATO military alliance will never expand to include Ukraine, which has long sought membership. That’s a non-starter for the Americans and their NATO allies.

“We’ve consulted significantly with our allies and believe we have a path forward that would impose significant and severe harm on the Russian economy,” White House press secretary Jen Psaki said Monday in previewing the meeting. “You can call that a threat. You can call that a fact. You can call that preparation. You can call it whatever you want to call it.”

The leader-to-leader conversation — Biden speaking from the Situation Room, Putin from his residence in Sochi — is expected to be one of the toughest of Biden’s presidency and comes at a perilous time. U.S. intelligence officials have determined that Russia has massed 70,000 troops near the Ukraine border and has made preparations for a possible invasion early next year.

The U.S. has not determined whether Putin has made a final decision to invade. Still, Biden intends to make clear to the Russian leader that there will be a “very real cost” should Russia proceed with military action, according to a senior administration official who briefed reporters on the condition of anonymity.