In a high-stakes video conference with Vladimir Putin on Tuesday, Joe Biden told him that the US and Europe were prepared to inflict nuclear economic sanctions if Russia invaded Ukraine.

The contentious encounter was one of Biden's most important tests to date. Washington saw it as a last-ditch effort to defuse tensions over suspicions that Moscow is poised to strike its neighbor.

According to the White House, Biden made it "crystal clear" to Putin that if a military escalation along the border occurred, the West would be prepared to apply severe sanctions. According to Downing Street, Boris Johnson talked with his American, French, German, and Italian counterparts to follow up with Biden on his call with Russian President Vladimir Putin.

Biden warns Putin on Ukraine

The leaders underlined the necessity of Russia discontinuing their threatening actions towards Ukraine and agreed on the importance of an "ongoing conversation" with Russia, as per The Daily Telegraph. They discussed the "severe repercussions of Russian military activity in Ukraine and the need to de-escalate and return to negotiations," according to the White House.

Biden's national security adviser, Jake Sullivan, claimed the US was in "lockstep" with its allies. Any invasion of Ukraine would jeopardize the contentious Russia-Germany Nord Stream 2 pipeline, according to Sullivan.

Biden has made "no compromises" to Putin on Ukraine's ambition to join NATO. He said that the US still didn't know if Putin had made up his mind about invading. According to Sullivan, Biden informed Putin that if the situation escalated, the US would assist Ukraine with more defensive material and "fortify our Nato allies on the eastern flank with further capabilities."

The video conference meeting between Biden and Putin occurred amid mounting concern about US intelligence reports of a Russian troop buildup near Ukraine's border, stoking fears of an invasion, USA Today reported.

According to Sullivan, the US believes Putin has yet to decide whether or not to invade Ukraine, but officials have stated that Russia is putting in place the means to do so if he so chooses. If Putin decides to attack Ukraine, Sullivan declined to say what economic measures the US and its allies may impose on Russia.

However, he added that Biden made it clear that, while he favors a diplomatic solution to the problem, the United States is prepared to take countermeasures if necessary. Those actions, according to Sullivan, would be far more severe than the sanctions implemented in 2014 in a failed attempt to prevent Russia from conquering Crimea.

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Trump says Putin "not worried" after call with Biden

Meanwhile, Donald Trump slammed President Joe Biden's treatment of Vladimir Putin amid the Russian president's force buildup near the Ukraine border, claiming Putin "is not worried" by his predecessor's handling of the Afghanistan exit.

Top Republicans have slammed the Biden administration's handling of the Afghanistan withdrawal on several occasions. According to reports released on Tuesday, the White House is considering withdrawing Americans from Ukraine if Russia launches an invasion to avoid another catastrophic situation.

Per NY Post, there are no active plans to remove Americans from the European country; officials are only trying to avoid being caught "flat-footed." During the confidential conversation, Biden and Putin addressed a range of issues. Still, the major focus was on Ukraine since Russia has been steadily growing its military presence along the Ukrainian border for months. New satellite footage released on Monday shows military assembling at numerous critical strategic areas in western Russia and Crimea.

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