President Biden raises concerns with Putin over Ukraine

President Joe Biden called on Russian President Vladimir Putin on Tuesday to “de-escalate tensions” following a Russian military buildup on Ukraine’s border.

Biden also told Putin the U.S. would “act firmly in defense of its national interests” regarding Russian cyber intrusions and election interference, according to the White House. Biden proposed a summit meeting in a third country “in the coming months” to discuss the full range of U.s.-russia issues, the White House said.

The call comes as concern rises in the West about a surge of ceasefire violations in eastern Ukraine, where Russia-baked separatists and Ukrainian forces have been locked in a conflict since Moscow’s 2014 annexation of Ukraine’s Crimean Peninsula.

“President Biden emphasized the United States’ unwavering commitment to Ukraine’s sovereignty and territorial integrity,” the White House said in a statement. The White House added that Biden made clear that Russia must “de-escalate tensions.”

More than 14,000 people have died in fighting in eastern Ukraine, and efforts to negotiate a political settlement have stalled. Over the past week, there have been daily reports of Ukrainian military casualties and rebels also have reported losses.

Ukraine has said Russia has massed 41,000 troops at its border with eastern Ukraine and 42,000 more in Crimea. Russia’s defense minister said Tuesday the buildup was part of readiness drills in response to what he described as threats from NATO, and he said the maneuvers in western Russia would last for two more weeks.

The Kremlin said “during an exchange of opinions on Ukraine’s internal political crisis,” Putin told Biden about “approaches to a political settlement” based on the 2015 peace deal brokered by France and Germany and signed in Minsk, Belarus.

The two also discussed arms control, the Iranian nuclear program, the situation in Afghanistan and climate change, according to the Kremlin.

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.”

KREMLIN POOL PHOTO VIA AP Russian President Vladimir Putin visits the Coordination Center of the Russian Government in Moscow on Tuesday. The center was set up as a line of communication for analyzing and collecting information, promptly using big data and solving arising problems.