MOSCOW (AP) — French President Emmanuel Macron is set to hold talks in Moscow Monday in a bid to to help de-escalate the tense situation around Ukraine.

The concentration of an estimated 100,000 Russian troops near Ukraine has fueled Western worries that it heralds a possible offensive, with White House national security adviser Jake Sullivan warning Sunday that Russia could invade Ukraine “any day,” triggering a conflict that would come at an “enormous human cost.”

Russia has denied any plans to attack its neighbor, but is urging the U.S. and its allies to bar Ukraine and other ex-Soviet nations from joining NATO, halt weapons deployments there and roll back NATO forces from Eastern Europe. Washington and NATO have rejected the demands.

Macron, who is set to meet in the Kremlin with Russian President Vladimir Putin before visiting Ukraine Tuesday, said last week that his priority is “dialogue with Russia and de-escalation.”

Before heading to Moscow, Macron had a call Sunday with U.S. President Joe Biden. They discussed “ongoing diplomatic and deterrence efforts in response to Russia’s continued military build-up on Ukraine’s borders, and affirmed their support for Ukraine’s sovereignty and territorial integrity,” the White House said in a statement.