- Russia says it told U.S. Ambassador John Sullivan that President Joe Biden's decision to label Russian President Vladimir Putin a "war criminal" has put "Russian-American relations on the verge of rupture."
- Biden said Wednesday that he believes Russian leader Vladimir Putin "is a war criminal" for his attacks on Ukraine. It was the first time Biden had publicly branded Putin with that phrase.
- The diplomatic breakdown comes as Russia nears the one-month point in its unprovoked invasion of Ukraine.
The Russian Ministry of Foreign Affairs said it summoned U.S. Ambassador John Sullivan on Monday in Moscow to formally protest President Joe Biden's decision last week to label Russian President Vladimir Putin a "war criminal."
Sullivan was told that Biden's accusation had put "Russian-American relations on the verge of rupture," according to a statement from the Foreign Ministry translated by NBC News.
Biden's comment came hours Ukrainian President Volodymyr Zelenskyy and other top officials met virtually with the International Criminal Court's top prosecutor, who two weeks ago opened an investigation into possible war crimes by Russia.
A State Department spokesperson did not immediately respond to a request for comment Monday from CNBC.
But the U.S. Embassy in Moscow tweeted that Sullivan met with Russian diplomats in order to demand consular access to U.S. citizens detained in Russia, "including those in pretrial detention."
American WNBA star player Brittney Griner is currently being held in pretrial detention outside Moscow on allegations of smuggling drugs. The American Embassy did not mention Griner by name in its tweet.
Sullivan is a Trump-era appointee whom the U.S. president asked to stay on at the start of Biden's term in 2021.
The diplomatic breakdown comes as Russia nears the one-month point in its unprovoked invasion of Ukraine, which was launched Feb. 24.
An initial Russian infantry advance has largely stalled outside of the country's major cities amid fierce Ukrainian resistance. This has forced the Kremlin to shift tactics from a quick land war to a conflict of attrition marked by the shelling of residential areas in an effort to wear down and demoralize the nation.
White House press secretary Jen Psaki later said Biden was speaking from his heart about what he has seen on the news about the "barbaric actions by a brutal dictator."
Psaki noted there is a separate legal process to determine whether Putin has violated international law and committed war crimes. That process currently is underway at the State Department, she said.
While the formal process proceeds slowly, top officials in the Biden administration have openly alleged that Putin is a war criminal and that Russia is committing war crimes in Ukraine.
One day after Biden's comment, Secretary of State Antony Blinken said, "Personally, I agree" with the president's assessment of Putin.
“Intentionally targeting civilians is a war crime. After all the destruction of the past three weeks, I find it difficult to conclude that the Russians are doing otherwise," said Blinken.
Correction: Secretary of State Antony Blinken said, "Personally, I agree" with the president's assessment of Putin. An earlier version misspelled Blinken's first name.