US officials say Russia at 70 percent of buildup needed for invasion: reports

Russia has assembled 70 percent of the military forces needed to launch a massive invasion of Ukraine that could result in tens of thousands of civilian deaths and millions of refugees, according to U.S. military and intelligence officials.

Senior Biden officials warned in briefings to lawmakers and European partners in recent days that if Moscow elects to launch a full invasion of Ukraine, 50,000 civilians could be killed and up to 5 million refugees could result, multiple news outlets reported on Saturday, including The Washington Post.

According to official U.S. assessments, Russian President Vladimir Putin has 83 battalion tactical groups of roughly 750 troops each on the border of Ukraine, amounting to 70 percent of the forces he would need to maximize a full invasion, the Post reported.

Officials have estimated there are more than 100,000 Russian troops amassed on the Ukrainian border. The buildup is considered not to be a bluff and an attack is believed possible any day, with optimal conditions for an invasion projected to occur between mid-February and late March, the Post reported.

The news come two days after U.S. lawmakers left classified briefings with defense officials warning that a Russian invasion of Ukraine could be imminent.

Sen. Marco Rubio (R-Fla.) told reporters after the meeting that an invasion was a "near certainty."

"This is the most significant threat in Europe since 1945," he said.

The Pentagon has deployed 3,000 troops to Eastern Europe and has put another 8,500 troops on heightened alert to deploy amid the ongoing tensions between Russia and Ukraine, though the administration has repeatedly said there are no plans to send American forces into Ukraine.

Russia has denied having any intention of invading Ukraine and at a United Nations Security Council meeting on Monday accused the U.S. of stoking hysteria.

Russian Ambassador Vasily Nebenzya said U.S. officials were "almost calling for" the invasion to happen.

"You want it to happen, you're waiting for it to happen, as if you want to make your words become a reality," the ambassador said.

According to assessments from U.S. officials, the window for the tensions to be solved diplomatically appears to be ending, sources familiar told the Post.

Putin on Tuesday said the U.S. and NATO had "ignored" Russian concerns and accused the U.S. of leading Russia into a conflict with Ukraine.

A day prior, President Biden had said the U.S. and its allies would continue to negotiate in good faith with Russian officials to address the country's security concerns, but that Russia would "face swift and severe consequences" if it invaded Ukraine.