Russia has amassed more troops on the Ukrainian border than at any time since 2014. Western governments are asking: Why now?

MOSCOW — Armored personnel carriers bristling with weapons line a highway in southern Russia. Rows of tanks are parked beside major roads. Heavy artillery is transported by train.

Videos of military movements have flooded Russian social media for the past month, shared by users and documented by researchers.

And Western governments are trying to find out why. The movements appear to be the largest deployment of Russian land forces toward the border with Ukraine in seven years, according to the U.S. government.

Whether it is a test of how the Biden administration might respond, retaliation against Ukraine for curbing Russian influence in domestic politics in Kyiv, or preparation for actual cross-border military action has divided analysts of Russian policies.

Another possible motive has been found closer to home: The very public military buildup — trains bearing armored vehicles have been rolling into the border region in broad daylight — has shifted attention from the imprisonment and failing health of President Vladimir V. Putin’s chief political opponent, Aleksei A. Navalny.

A still image taken from video showing a Russian military buildup this week in southern Russia.
Reuters

The Ukraine war, the only active conflict in Europe today, has been on a low simmer since 2015. Russian-backed separatists and the Ukrainian army have faced off along a 250-mile front of trenches known as the line of contact, shelling and sniping at one another but not seeking major advances.

The fighting picked up last month, with nine Ukrainian soldiers killed since late March.

On Friday, the Kremlin appeared to escalate the situation again by laying out a justification for military intervention on humanitarian grounds, discussing the prospect of a new war in the region in some of the starkest, most open terms yet.

The Kremlin spokesman, Dmitri S. Peskov, said Russia would intervene to prevent ethnic cleansing of Russian speakers by the Ukrainian government, a risk he compared to the ethnic massacres of the 1990s Balkan wars, though there are no signs that such violence is imminent in Ukraine today.

“The situation on the contact line in Ukraine is extremely unstable,” Mr. Peskov said. “If military actions begin and a potential repetition of a humanitarian catastrophe similar to Srebrenica arises, not one country in the world will remain on the sidelines. All countries, including Russia, will take measures.”

The comment was the second this week by a senior Russian official citing the Srebrenica massacre in Bosnia-Herzegovina in 1995 as a touchstone for justifying humanitarian intervention in Ukraine today.

Pool photo by Alexei Druzhinin

The bloody, hate-filled milieu of the 1990s Balkans is a poor analogy for the geopolitically driven conflict in eastern Ukraine.

In Bosnia in 1995, the United Nations had declared a safe zone in the city of Srebrenica but failed to prevent the Bosnian Serb army from entering and massacring more than 8,000 Muslim men and boys. The front line in Ukraine, in contrast, separates villages and towns comprising a similar mix of Ukrainian and Russian speakers, with no significant ethnic or sectarian differences.

Mr. Peskov said the risk arose from “actions of the Ukrainian military” and rising Ukrainian nationalism.

On Thursday, Russia’s chief negotiator in the Ukrainian peace process, Dmitri Kozak, offered another potential justification for intervention: to protect people with dual Ukrainian and Russian citizenship. Since 2019, Russia has been granting citizenship to residents of the two separatist enclaves in eastern Ukraine, the Donetsk and Luhansk people’s republics.

Russian officials have said Ukraine, not Russia, initiated the escalation. The Russian foreign ministry spokeswoman, Maria Zakharova, on Friday blamed Ukraine for mustering forces near the contact line and said Kyiv “lives with an illusion of a possible forceful settlement” of the conflict.

Pavel Golovkin/Associated Press

As talk of war has become louder, Chancellor Angela Merkel of Germany called on Mr. Putin this week to demand that forces pull back from the border. The White House spokeswoman, Jen Psaki, said Thursday the Biden administration is “increasingly concerned,” by the movements.

“Russia now has more troops on the border with Ukraine than at any time since 2014,” Ms. Psaki said, and Ukrainian soldiers have been dying in skirmishes. “These are all deeply concerning signs.”

Before the tanks started rolling, Russia had been telegraphing a possible response to the Biden administration’s promise of a tougher line with Moscow. The Biden administration had said it would pursue cyberoperations and sanctions to retaliate for Russian cyberattacks and election meddling.

Russia, some analysts say, is now essentially daring the United States to follow through while its tanks are on the Ukrainian border.

The U.S. threat of a cyberoperation against Russia in particular prompted Mr. Putin in January to hint at troubles ahead, according to Konstantin Eggert, an observer of Russian politics. “Such a game with no rules,” Mr. Eggert wrote, led Mr. Putin to warn in a speech given to the Davos Forum of an “increase in the risk of unilateral use of military force,” refraining from mentioning which country might be using that force.

Sergey Ponomarev for The New York Times

The pace of military movements picked up in March, according to the Conflict Intelligence Team, a group of Russian military bloggers who analyzed images and videos posted online by Russians who watched the columns go by. Their report was published in the Insider, a Russian investigative news site.

A wide range of weaponry has been on public display. In March, for example, a train hauling Msta-C self-propelled howitzers rumbled over a bridge across the Kerch Strait separating Russia’s mainland from Crimea.

The Russian airwaves, too, have been chockablock with reports of a possible resumption of war in eastern Ukraine.

“Bad news from Ukraine,” the commentator Dmitry Kiselyov said in opening his Sunday talk show this week on state Channel 1. “The talk in Ukraine is increasingly about war.”

Mr. Kiselyov mocked war jitters in Ukraine, where the government has been trying to portray a calm resolve; the president, Volodymyr Zelensky, visited the front on Thursday.

The Russian state television report lingered on an incident in the Ukrainian Parliament this month when a lawmaker, Anna Kolesnik, after hearing a presentation from a military commander on the scale of Russia’s forces massed at her nation’s border, wrote a phone message to an acquaintance saying, “it’s time to split from this country.”

Mr. Kiselyov noted that in Ukraine, “the fear is inflating.”

Michael Kofman, a senior researcher at CNA, an analytical organization based in Arlington, Va., said the Russian buildup seems targeted more at shifting Ukraine’s stance in settlement talks than countering U.S. sanctions.

“Saber-rattling is an oversimplification,” he said. “It is coercive diplomacy with a purpose,” though for now that purpose is unstated and left open to interpretation by Ukraine and Western governments. “That is the situation we are in.”