Ukraine complained last week that Russia has kept tens of thousands of troops not far from the two countries' borders after conducting war games in an attempt to exert further pressure on its ex-Soviet neighbor. Russia annexed Ukraine's Crimean Peninsula in 2014 and has supported a separatist insurgency that broke out that year in eastern Ukraine.

The Ukrainian Defense Ministry claimed that about 90,000 Russian troops are stationed not far from the border and in rebel-controlled areas in Ukraine’s east. It said units of the Russian 41st army have remained in Yelnya, a town about 260 kilometers (about 160 miles) north of the Ukrainian border.

U.S. Secretary of State Antony Blinken assured the Ukrainian foreign minister, Dmytro Kuleba, in Washington this week that the U.S. commitment to Ukraine’s security and territorial integrity is “ironclad.”

Blinken said the United States did not know Russia’s intentions but that Moscow’s “playbook” in the past has included inventing alleged provocations along its border to justify military intervention.

Russia has cast its weight behind the separatist insurgency in Ukraine’s east that has left more than 14,000 dead. But Moscow has repeatedly denied any presence of its troops in eastern Ukraine.

Asked Thursday if Russia planned to invade Ukraine, Russia’s deputy U.N. ambassador, Dmitry Polyansky, replied that it “never planned, never did, and (is) never going to do it unless we’re provoked by Ukraine, or by somebody else.” He cited what he called many threats from Ukraine and allegedly provocative actions by U.S. warships in the Black Sea.

Peskov similarly emphasized Friday that Russia needs to protect its security amid what he described as “increasing provocations” near its borders. He pointed at the U.S. naval deployment to the Black Sea and increasingly frequent U.S. and NATO intelligence flights.

“We take measures to ensure our security when our opponents take defiant action near our borders,” Peskov said. "We can't stay indifferent to that; we must be on our guard.”

The Russian Defense Ministry described the deployment of the U.S. warships USS Mount Whitney and USS Porter, which sailed into the Black Sea last week, as a “threat to regional security and strategic stability.”

“The real goal behind the U.S. activities in the Black Sea region is exploring the theater of operations in case of Kyiv's attempts to settle the conflict in the southeast by force,” the ministry said in a statement.

The reported Russian military buildup near Ukraine also raised concern in the European Union.

Earlier this week, European Commission President Ursula von der Leyen said after discussing the issue with U.S. President Joe Biden that “we fully support the territorial integrity of Ukraine.”

European Commission spokesperson Peter Stano told reporters Friday that the bloc is discussing the situation with partners, including the U.S. and United Kingdom, adding that “the information we gathered so far is rather worrying.”