MOSCOW — 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 called for de-escalation as he began talks with Russian President Vladimir Putin in the Kremlin. “Dialogue is necessary because that’s the only thing that will help, in my views, to build a context of a security and stability on the European continent,” Macron said, adding that he’s ready to “start building an effective response.”

Putin, in turn, hailed France’s role in shaping European security and noted that he appreciates Macron’s efforts to help ensure “an equal security in Europe” and broker a settlement to the Ukrainian crisis. “I realize that we share concern about what’s going on in Europe in the security sphere,” the Russian leader said as he faced Macron across a long table.

Macron, who heads Tuesday to Ukraine, spoke by phone Sunday with U.S. President Joe Biden on “ongoing diplomatic and deterrence efforts,” according to the White House.

Before the meeting, Macron said: “I don’t believe in spontaneous miracles.”

“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 he believes “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 the 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.

Before his meeting with Biden, Scholz told German media that the talks would ensure all allies were unified.

“There will be a very high price if Ukraine is attacked militarily,” said Scholz, who will travel to Kyiv and Moscow on Feb. 14-15. “And we are preparing for this very precisely and have been talking about the details for a long time.”

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 their first face-to-face meeting since Scholz became the head of the German government nearly two months ago.

German Foreign Minister Annalena Baerbock said on a visit to Kyiv that her country is prepared to pay a “high economic price” by slapping tough sanctions on Russia if it invades Ukraine.

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.

German Defense Minister Christine Lambrecht said Monday it will add up to 350 troops within a few days to about 500 already a part of a NATO battlegroup in Lithuania. “With this, we are strengthening our contribution to forces on NATO’s eastern flank and sending a very clear signal of unity to our allies,” she said.

Biden already has deployed additional U.S. troops to Poland, Romania and Germany, and a few dozen elite U.S troops and equipment landed Sunday in southeastern Poland near the border with Ukraine, with hundreds more infantry troops of the 82nd Airborne Division set to arrive.

Britain said it was sending 350 troops to Poland to bolster NATO forces, joining 100 Royal Engineers already there.

NATO Secretary-General Jens Stoltenberg said the alliance is weighing a more permanent military presence in southeast Europe in response to Russia’s “massive military deployment” near Ukraine.

“We are considering more longer-term adjustments to our posture, our presence in the eastern part of the alliance,” Stoltenberg said after talks in Brussels with Polish President Andrzej Duda. “If Russia really wants less NATO close to the borders, they get the opposite.”

Stoltenberg gave no details and said no final decision has been made, but the move could mirror NATO’s long-term military presence in Estonia, Latvia, Lithuania and Poland, where about 5,000 troops are stationed. It would see a similar force based in Bulgaria, Romania, Hungary and Slovakia.

That would mean NATO troops stationed long-term near Ukraine’s western border and in the Black Sea area. The aim would be only to bolster the defenses of NATO allies in the region and the troops would not cross into Ukraine should Russia invade.

In 2015, France and Germany helped broker a peace deal for eastern Ukraine in a bid to end the conflict between Ukrainian forces and Russia-backed separatists that erupted the previous year following the Russian annexation of Ukraine’s Crimean Peninsula.

The agreement signed in the Belarusian capital of Minsk helped stop large-scale fighting, but efforts at a political settlement have stalled and frequent skirmishes have continued along the tense line of contact in Ukraine’s industrial heartland known as the Donbas.

Putin and his officials have urged France, Germany and other Western allies to encourage Ukraine to fulfill its obligations under the 2015 agreement, which envisaged a broad autonomy for the Donbas region and a sweeping amnesty for the separatists. The agreement stipulated that only after those conditions are met would Ukraine be able to restore control of its border with Russia in rebel regions.

The Minsk deal was seen by many Ukrainians as a betrayal of national interests, and its implementation has stalled. Ukrainian authorities have warned the West against pressuring Ukraine to implement the agreement.

Ukraine’s Foreign Minister Dmytro Kuleba said the country has received more than 1,000 metric tons of weapons and military supplies from its allies, noting that a series of visits by Western officials has helped deter Russia.