Russia tells US envoy that Russian-American relations are on the verge of rupture

The Russian Foreign Ministry said Monday that it had summoned the U.S. ambassador to warn that President Joe Biden's recent remarks have put Russian-American relations on the verge of rupture.

Biden last week described Russian President Vladimir Putin as a "war criminal" as Russia's missile attacks on Ukraine cities intensified. The Foreign Ministry, in a social media post, called the statement and other references to Putin and the Russian invasion "unworthy of a statesman of such high rank."

The ministry warned Ambassador John Sullivan that hostile actions taken against Russia would be met with a "decisive and firm rebuff."

The warning came hours after Ukraine firmly rejected a Russian offer to open two safe corridors out of Mariupol in exchange for the city's surrender as the relentless missile strikes on the battered seaport city stretched deeper into a fourth week.

Russian forces, facing stiff resistance against their invasion of Ukraine, have sought to gain control of cities but can claim few successes thus far. The Kremlin says its "special operation" is going as planned. But a senior Pentagon official, who spoke on condition of anonymity Monday, said Russian President Vladimir Putin has not achieved his goals and is relying on bombardment of cities in a “near-desperate” effort to gain momentum.

Mariupol, crucial for its access to the Sea of Azov, has been pounded by Russian artillery since the war began more than three weeks ago. Russian forces have been accused of bombing civilian shelters, and hundreds of thousands have recently fled the city.

Ukrainian Deputy Prime Minister Iryna Vereshchuk made it clear that Mariupol won't fall without a fight.

“There can be no talk of any surrender, laying down of arms," she told Ukrainian Pravda. "We have already informed the Russian side about this."

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