The conflict — and an overtly threatened Russian invasion that the talks are intended to forestall — is in Ukraine.

Fearing the talks will yield little or nothing, and with President Biden’s statement that the United States will not intervene militarily if Russia invades, Ukraine has quietly pursued its own negotiating track with Moscow.

The latest threat of invasion began last month, when Russia massed more than 100,000 troops along its borders with Ukraine and demanded wide-ranging — and, to Western analysts, impossible — concessions from the United States and NATO on matters of European security.

Putin of Russia subsequently threatened to launch an invasion of Ukraine if the talks on its proposals should fail.

In effect, that made Ukraine “the hostage,” of Russia, said Kostiantyn Yelisieiev, a former Ukrainian ambassador to the European Union.

Moscow’s sidelining of Ukraine and its demand for direct talks with the United States and NATO were intentional, Mr.

The talks got off to a rocky start on Sunday when a senior Russian official warned that the United States had a “lack of understanding” of the Kremlin’s security demands, and the United States voiced doubts over whether Russia was “serious” about de-escalating the crisis in Ukraine.

Blinken said the United States was “not about making concessions” under the threat of a Russian invasion of Ukraine, eight years after it annexed Crimea.

Russia intervened militarily in Ukraine in 2014, annexing the Crimean Peninsula and fomenting separatist uprisings in two eastern provinces, leading to the deaths of more than 13,000 people.

“The issues concern all of Europe, including Ukraine, but Putin suggests discussions between Russia and the United States,” Mr.

The United States has said it is coordinating closely with the authorities in Kyiv, and Mr.

Zelensky announced a separate, Ukrainian diplomatic initiative with Russia in late December, the specifics of which were later published in the Russian newspaper Kommersant.

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.

Russia called the strike a destabilizing act that violated the cease-fire agreement, raising fears of a new intervention in Ukraine that could draw the United States and Europe into a new phase of the conflict.

Putin of Russia, who has increasingly portrayed NATO’s eastward expansion as an existential threat to his country, said that Moscow’s military buildup was a response to Ukraine’s deepening partnership with the alliance.

To date, none of the diplomatic talks with Russia, whether with the United States or Ukraine, have slowed the stream of ominous statements from Russian officials that diplomats and analysts worry could be used to justify military action or prepare the Russian population for a war.

The threats became more focused in August after the American withdrawal from Afghanistan, when senior Russian security officials publicly taunted Ukraine that it, too, could soon lose the United States as a protector.

A deputy foreign minister for Russia, Aleksandr Grushko, more explicitly linked a threat of Russian military force to a breakdown in the talks