Biden proposes summit amid tensions over Russia's military buildup near Ukraine

U.S. President Joe Biden proposed a summit meeting with Russian President Vladimir Putin during a telephone call on Tuesday in which he stressed the U.S. commitment to Ukraine's territorial integrity and voiced concern about a Russian military buildup in Crimea and on Ukraine's borders, the White House said.

"President Biden also made clear that the United States will act firmly in defence of its national interests in response to Russia's actions, such as cyber intrusions and election interference," the White House said in a brief statement.

"President Biden emphasized the United States' unwavering commitment to Ukraine's sovereignty and territorial integrity. The president voiced our concerns over the sudden Russian military buildup in occupied Crimea and on Ukraine's borders, and called on Russia to de-escalate tensions," the statement read. 

The conversation was only the second between the two leaders since Biden became president on Jan. 20 and it took place amid growing U.S. and European concerns about Russian treatment of Ukraine.

Largest massing of troops since annexation

Western officials say Russia has moved thousands of combat-ready troops to Ukraine's borders this year, the largest massing of Russian troops since it seized Crimea from Ukraine in 2014. Fighting has escalated in recent weeks in eastern Ukraine, where government forces have battled Russian-backed separatists in a seven-year conflict that Kyiv says has killed 14,000 people.

"President Biden reaffirmed his goal of building a stable and predictable relationship with Russia consistent with U.S. interests, and proposed a summit meeting in a third country in the coming months to discuss the full range of issues facing the United States and Russia," the White House statement said.

Ukraine has said Russia has accumulated 41,000 troops at its border with eastern Ukraine and 42,000 more in Crimea.

Drills to 'ensure the country's security'

Russian Defence Minister Sergei Shoigu said Tuesday the buildup was part of readiness drills in response to what he described as threats from NATO, and he said the manoeuvres in western Russia would last for two more weeks.

Speaking at a meeting with the top military brass, Shoigu said the ongoing exercise was a response to what he claimed were continuous efforts by the United States and its NATO allies to beef up their forces near Russia's borders.

"The troops have shown their full readiness to fulfil tasks to ensure the country's security," he said.

Earlier Tuesday, Secretary of State Antony Blinken, who was in Brussels for meetings with NATO allies, accused Russia of taking "very provocative" actions with the amassing of troops.

NATO chief Jens Stoltenberg also called the Russian movements "unjustified, unexplained and deeply concerning."

Ukrainian Foreign Minister Dmytro Kuleba said Kyiv welcomed the support and urged Western countries to make clear to Moscow that it would pay a price for its "aggression."