MOSCOW (AP) - International efforts to defuse the standoff over Ukraine intensified Monday, with French President Emmanuel Macron holding talks in Moscow and German Chancellor Olaf Scholz in Washington to coordinate policies as fears of a Russian invasion mounted.

The buildup of an estimated 100,000 Russian troops near Ukraine has fueled Western worries of a possible offensive. White House national security adviser Jake Sullivan warned 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 demands that the U.S. and its allies bar Ukraine and other former Soviet nations from joining NATO, halt weapons deployments there and roll back NATO forces from Eastern Europe. Washington and NATO reject those demands.

Macron, who is set to meet in the Kremlin with Russian President Vladimir Putin before visiting Ukraine on Tuesday, spoke by phone Sunday with U.S. President Joe Biden to discuss “ongoing diplomatic and deterrence efforts,” according to the White House.

“The security and sovereignty of Ukraine or any other European state cannot be a subject for compromise, while it is also legitimate for Russia to pose the question of its own security,” Macron said in an interview with French newspaper Journal du Dimanche, adding that he believes that “the geopolitical objective of Russia today is clearly not Ukraine, but to clarify the rules of cohabitation with NATO and the EU.”

Putin’s spokesman, Dmitry Peskov, described Macron’s visit as “very important,” but sought to temper expectations, saying “the situation is too complex to expect a decisive breakthrough after just one meeting.”

He noted that “the atmosphere has remained tense,” adding that the U.S. and its allies have continued to ignore Moscow’s security demands.

Continuing the high-level diplomacy, Scholz is to meet with Biden later Monday in Washington. Scholz is set to travel to Kyiv and Moscow on Feb. 14-15.

Sullivan, the national security adviser, reiterated Sunday that the Russian Nord Stream 2 gas pipeline to Germany “will not move forward” if Russia attacks Ukraine.

Biden and Scholz are expected to address the pipeline during their first face-to-face meeting since Scholz became the head of the German government nearly two months ago. Ahead of the visit, the White House sought to play down Germany’s refusal to supply lethal weapons to Ukraine, bolster its troops in Eastern Europe or spell out which sanctions it would support against Russia - a cautious stand that has drawn criticism abroad and inside Germany.

White House officials, who briefed reporters ahead of the meeting on the condition of anonymity, noted that Germany has been a top contributor of nonmilitary aid to Ukraine and has been supportive of the U.S. decision to bolster its troop presence in Poland and Romania to demonstrate its commitment to NATO.