KYIV, Ukraine — President Biden warned President Vladimir V. Putin of Russia that invading Ukraine would result in “swift and severe” costs to Russia, diminish his country’s standing and cause “widespread human suffering,” the White House said on Saturday, as Western officials made a forceful diplomatic push to dissuade Mr. Putin from pressing forward with an attack.
It remained uncertain whether Mr. Putin would invade, according to senior Biden administration officials. But after the call, one official said that the situation remained as urgent as it was on Friday when the administration said Russia could invade at any moment and Jake Sullivan, the president’s national security adviser, warned Americans to leave the country in the coming days.
White House officials said that Mr. Biden discussed a range of diplomatic options with Mr. Putin, but that it was unclear if Mr. Putin was persuaded to take that route.
A foreign policy aide to Mr. Putin, Yuri Ushakov, described the call with Mr. Biden as “businesslike” but overshadowed by American “hysteria” over a possibly imminent Russian invasion of Ukraine. He said that Mr. Putin would consider Mr. Biden’s proposals, but that they ignored Russia’s key demands for “security guarantees” in Eastern Europe, including a legally binding halt to NATO expansion and a pullback of the alliance’s military presence in the region.
And Mr. Ushakov continued to reject the idea that Russia was threatening a war. “We have repeatedly underlined that we don’t understand why the news media should be given clearly false information about Russian plans,” he said.
But one American national security official, who briefed reporters shortly after the call, said that there was “no fundamental change in the dynamic that has unfolded now for several weeks,” an acknowledgment that Mr. Putin has continued to build up a military presence that has effectively surrounded Ukraine.
The two leaders spoke only hours after the United States ordered most of its diplomats and other staff members to leave the American Embassy in Ukraine, amid mounting fears that Russia’s huge buildup of forces on land and at sea around Ukraine signaled that an invasion was imminent.
A senior State Department official said on Saturday that the drawdown at the embassy, one of America’s largest in Europe, reflected the urgent need for American citizens to leave Ukraine immediately because Washington would have a limited ability to help them if the country became a “war zone.”
In a sign of the mounting anxiety, Defense Secretary Lloyd J. Austin III ordered a “temporary” repositioning of 160 National Guard trainers from Ukraine to “elsewhere in Europe,” the Pentagon said on Saturday. The trainers have been working alongside an undisclosed number of Army Green Berets, who will remain in Ukraine for now, officials said.
Despite the warnings, American officials believe that Mr. Putin may not yet have made a final decision to invade, and the West’s diplomatic scramble continued on Saturday. President Emmanuel Macron of France spent one hour and 40 minutes on the phone with Mr. Putin, Mr. Macron’s office said.
Secretary of State Antony J. Blinken and Mr. Austin made separate calls to their Russian counterparts on Saturday. And President Volodymyr Zelensky of Ukraine continued to play down the threat, expressing frustration with Washington.
“The best friend for enemies is panic in our country,” Mr. Zelensky told reporters, in English, while observing a police training exercise in southern Ukraine. “And all this information — that helps only for panic, doesn’t help us.”
Mr. Putin is likely to offer more public clues to his position in the coming days. Mr. Ushakov said Russia’s response to last month’s American security proposals would be made public soon. On Tuesday, Chancellor Olaf Scholz of Germany will travel to Moscow, after holding talks in Kyiv, Ukraine’s capital, the previous day. And on Wednesday — the day that American officials have said a Russian invasion could begin — Mr. Putin is scheduled to host President Jair Bolsonaro of Brazil in Moscow.
The diplomatic flurry came as Russia’s military posture continued to grow more ominous. More than 30 Russian Navy ships — including frigates, missile boats and submarine chasers — set sail for exercises in the Black Sea, Russia’s Defense Ministry said. The deployment strengthened the effective encirclement of Ukraine by Russian forces from all sides but the west.
Ukrainian military officials have grown increasingly concerned about the deployment of special forces and airborne troops to regions near the Ukrainian border. Two days ago, the Kremlin deployed more than 50 attack and transport helicopters to Machulishchi in Belarus and Valuiki in Russia, both within easy striking distance of Ukraine, a senior Ukrainian military official said Saturday. Such helicopters would be used to provide close air support for any ground forces used in an invasion.
American officials believe that if Russia launches an invasion of Ukraine next week, it could be preceded by an operation meant to create a false pretext for the war, according to officials briefed on the intelligence. In recent days, American intelligence agencies have warned the Biden administration of a new so-called false-flag operation intended to fabricate a reason for Russia to invade, according to people briefed on the material.
The details of an attack, including its timing, were unclear.
In Kyiv on Saturday, several thousand people marched in a show of support for Ukraine and to oppose any possible settlement agreement with Russia that would weaken Ukrainian sovereignty.
At Boryspil airport, some foreign residents of Ukraine were lining up for flights out, though many were flying for reasons unrelated to the Russian military threat. Those leaving on flights on Saturday morning included relatives of Dutch and South Korean diplomats, a family from Denmark acting on warnings from the Danish government, employees of foreign companies and exchange students.
“The U.S. government was really pressing” a message of threat, Yollanda Mateosh, 19, an exchange student from Mozambique, said of his decision to leave Ukraine on Saturday, cutting short his course of study.
KLM, the main Dutch airline, announced on Saturday that it would stop flying to Ukraine, according to Dutch media. The news followed the Dutch government’s travel advisory that asked its citizens in Ukraine to leave immediately because of the worsening security situation.
At the American Embassy compound, local Ukrainian staff members carried dozens of plastic bags and loaded them into cars. Some carried out potted plants. All declined to answer questions. At one point, a gigantic stack of pizzas was delivered.
As of last month, the embassy in Kyiv had 181 American diplomats and officials from other government agencies and more than 560 Ukrainian employees. The State Department official said that a couple thousand Americans in Ukraine had reached out and advised the embassy of their whereabouts, but it did not provide a precise estimate of how many Americans were in Ukraine.
The official told reporters that the removal of most American diplomats from Kyiv should not be seen as diminishing U.S. support for Ukraine. Even as embassy employees were preparing to depart, the official said, American weaponry for the Ukrainian Army was arriving in the capital.
Understand the Escalating Tensions Over Ukraine
A brewing conflict. Antagonism between Ukraine and Russia has been simmering since 2014, when the Russian military crossed into Ukrainian territory, annexing Crimea and whipping up a rebellion in the east. A tenuous cease-fire was reached in 2015, but peace has been elusive.
A spike in hostilities. Russia has been gradually building up forces near its border with Ukraine, and the Kremlin’s messaging toward its neighbor has hardened. Concern grew in late October, when Ukraine used an armed drone to attack a howitzer operated by Russian-backed separatists.
Preventing an invasion. Russia called the strike a destabilizing act that violated the cease-fire agreement, raising fears of a new intervention in Ukraine. Since then, the United States, NATO and Russia have been engaged in a whirlwind of diplomacy aimed at averting that outcome.
The Kremlin’s position. President Vladimir V. Putin of Russia, who has increasingly portrayed NATO’s eastward expansion as an existential threat to his country, said that Moscow’s growing military presence on the Ukrainian border was a response to Ukraine’s deepening partnership with the alliance.
Rising tension. Western countries have tried to maintain a dialogue with Moscow. But the Biden administration warned that the U.S. could throw its weight behind Ukraine in case of an invasion. France, Germany and Poland also warned Russia of consequences if it launched incursions into Ukraine.
The official said efforts were also underway at the embassy to destroy or otherwise reduce classified documents and equipment.
Russia’s Foreign Ministry said it had also decided to reduce the staffing of its missions in Ukraine, which include an embassy in Kyiv and consulates in Lviv, Odessa and Kharkiv.
“We are drawing the conclusion that our American and British colleagues seem to know about certain military actions being prepared in Ukraine,” Maria V. Zakharova, the Foreign Ministry’s spokeswoman, said in a statement. “Our embassy and consulates will continue to exercise their main functions.”
Mr. Zelensky, the Ukrainian president, played down the American warnings of an imminent invasion, urging calm and claiming he had not seen intelligence showing that Russia was poised to attack. He told reporters that there was “too much information in the information space” about a possible full-scale war with Russia, and he ridiculed news reports that Russia could be planning to invade on Feb. 16.
Mr. Zelensky has, for weeks, expressed frustration with the American messaging on the crisis, criticizing the Biden administration for sowing panic in Kyiv and harming Ukraine’s economy. American officials respond that they are reacting to their intelligence, and they hope that calling Mr. Putin out publicly on his possible invasion plans could help deter him from taking action.
The French government said in its readout of Mr. Macron’s call with Mr. Putin that the two leaders had discussed “ways of moving forward” with implementing a 2015 peace plan for eastern Ukraine and had continued talks over the “conditions of security and stability in Europe.”
In a statement about the call with Mr. Macron, the Kremlin described warnings of a Russian invasion as “provocative speculation.” At the same time, the Kremlin said, the West was “pumping” Ukraine full of modern weaponry and “creating the conditions” for a Ukrainian attack on Russia-backed separatists in the country’s east.
Mr. Blinken, in his call with Russia’s foreign minister, Sergey V. Lavrov, on Saturday, warned that “should Moscow pursue the path of aggression and further invade Ukraine, it would result in a resolute, massive, and united trans-Atlantic response,” the State Department said.
But Mr. Lavrov apparently remained dismissive of the dire warnings, insisting that it was the United States that was worsening tensions and was seeking to encourage the Ukrainian government to attack the Russia-backed separatists in the country’s east.
But just outside Ukraine’s borders, Russia continued to mass forces. The 30 warships whose departure the Defense Ministry announced on Saturday will join other Russian vessels, including amphibious landing craft, that have arrived in the waters south of Ukraine over the past few weeks, many from distant ports in the Arctic Ocean and the Baltic Sea. In Ukraine’s southwest, on the border with Moldova, where Russia maintains forces in the breakaway region of Transnistria, Russian snipers took part in a shooting competition and military engineers conducted a training session.
And in Belarus to the north, large-scale exercises scheduled to end on Feb. 20 continued, including with a large-scale mock tank battle, according to a video published by the Russian Defense Ministry.
Andrew E. Kramer reported from Kyiv, Anton Troianovski from Moscow, and Lara Jakes and Katie Rogers from Washington. Reporting was contributed by Michael Schwirtz from Kherson, Ukraine; Ivan Nechepurenko from Sochi, Russia; Maria Varenikova from Kyiv; Eric Schmitt and Julian E. Barnes from Washington; and Aurelien Breeden from Paris.