U.S. Says Russia Lied About Troop Withdrawals as Shells Hit Ukrainian Kindergarten, Moscow Expels Diplomat

America believes the likelihood of an attack by Russia against Ukraine remains "very high," President Joe Biden said Thursday as he and other top U.S. officials adamantly disputed Russia's claim that it was drawing back troops from the country's border with Ukraine.

"They have not moved any of their troops out. They've moved more troops in," Biden, 79, said Thursday morning. "We have reason to believe that they are engaged in a false-flag operation to have an excuse to go in. Every indication we have is they're prepared to go into Ukraine and attack Ukraine."

Earlier this week, Russia said some of the 150,000 troops were retreating from the border and its defense ministry released a video that showed armored vehicles on the move, according to NBC News.

"They received a lot of attention for that claim both here and around the world, but we now know it was false," a senior Biden administration official told reporters on Wednesday. "In fact, we have now confirmed that in the last several days, Russia has increased its troop presence along the Ukrainian border by as many as 7,000 troops, with some arriving as recently as today."

Secretary of Defense Lloyd Austin reiterated the U.S. assertion that Russia is likely strengthening its forces as it prepares for a possible invasion.

In addition to adding troops, Austin said Thursday at NATO headquarters in Brussels that Russia is flying in more combat and support aircraft, working to "sharpen their readiness in the Black Sea" and "stocking up their blood supplies," CNN reports.

"I was a soldier myself not that long ago," Austin said, The New York Times reports. "I know firsthand that you don't do these sorts of things for no reason. And you certainly don't do them if you're getting ready to pack up and go home."

A Kremlin spokesman insisted a withdrawal was underway. "This process takes time," Dmitri S. Peskov said, according to the Times. "They cannot just get lifted in the air and fly away."

Russia also explicitly denied that 7,000 more troops arrived at the Ukraine border, and said there is no truth the the claim that it will invade this week, The Washington Post reports.

Secretary Blinken appeared at the United Nations' headquarters in New York City on Thursday morning and spoke about the escalating tensions in Europe, where Russia says it must satisfy its interests in neighboring Ukraine will limiting NATO's influence.

U.S. and Western European leaders, however, say its military moves risk shattering the balance of peace and igniting a major conflict.

"The most immediate threat to peace and security is Russia's looming aggression in Ukraine," Blinken said. "We must address what Russia is doing right now to Ukraine."

He also said the U.S. believes an attack by more than 150,000 Russian troops is on the horizon.

"Our information indicates clearly that these forces, including ground troops, aircraft, ships are preparing to launch an attack against Ukraine in the coming days," he said.

In announcing that Blinken would deliver remarks to the U.N. on Thursday, Linda Thomas-Greenfield, the American ambassador to the body, said, "Our goal is to convey the gravity of the situation" as Russia moves "towards an imminent invasion."

"This is a crucial moment," she added.

On Thursday, Russian-backed separatists in an eastern part of the country fired rounds of artillery that injured three people, disrupted power in the area and damaged a kindergarten in the village of Stanytsia Luhanska, the Ukraine military said.

The U.S. has previously warned that Russia could stage an attack or seek other ways to claim an invasion of its neighbor is justified, which Biden reiterated on Thursday in his remark about a "false-flag operation."

Blinken also expanded on what a Russia's plans "to manufacture a pretext for its attack" could look like.

"This could be a violent event that Russia will blame on Ukraine or an outrageous accusation that Russia will level against the Ukrainian government," he said Thursday. It could be a "fabricated so-called terrorist bombing inside Russia, the invented discovery of a mass grave, a staged drone strike against civilians … even a real attack using chemical weapons."

"Russia may describe this event as ethnic cleansing or a genocide," he added. "Russia media has already begun to spread some of these false alarms and claims to maximize public outrage to lay the groundwork."

In Moscow, the Deputy Chief of Mission at the U.S. Embassy there, Bart Gorman, was expelled from his post, according to reports.

"Russia's action against [Gorman] was unprovoked and we consider this an escalatory step and are considering our response," a State Deparment spokesperson said in a statement, CBS News reports.

"We call on Russia to end its baseless expulsions of U.S. diplomats and staff and to work productively to rebuild our missions," the spokesperson also said. "Now more than ever, it is critical that our countries have the necessary diplomatic personnel in place to facilitate communication between our governments."