President Biden told reporters Thursday that he believes Russia will invade Ukraine in a matter of days, describing the threat as “very high.”

“They [Russia] have not moved any of their troops out, they’ve moved more troops in, number one,” Biden said as he left the White House to travel to an event in Ohio. “Number two, 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,” the president added, “is that they are prepared to go into Ukraine, attack Ukraine.”

Biden reiterated that his “sense” is that an invasion ordered by Russian President Vladimir Putin “will happen in the next several days.”

The president noted that he still believes there is a diplomatic path to resolving the crisis – something the US and other Western allies have pushed in recent weeks – but added that he had “no plans” to speak with Putin “right now.”

As Biden left for Ohio, Vice President Kamala Harris departed Washington to travel to Germany for the high-level Munich Security Conference — where she is slated to give remarks about the Ukraine crisis as well as meet with Ukrainian President Volodymyr Zelensky and Germany Chancellor Olaf Scholz.

Harris will be joined in Munich by Secretary of State Antony Blinken, who warned the United Nations Security Council Thursday morning that Russian preparations for an invasion of Ukraine were “unfolding right now.”

Blinken, who greeted British diplomat James Cleverly with a fist-bump before his remarks, told the Security Council that “I am here today not to start a war, but to prevent one” and added that Moscow can still step back from the brink of full-fledged conflict. 

“The Russian government can announce today, with no equivocation or deflection, that Russia will not invade Ukraine,” Blinken said. “State it clearly, state it plainly to the world. And then demonstrate it by sending your troops, your tanks, your planes, back to their barracks and sending your diplomats to the negotiating table.”

Before the Security Council convened, US Ambassador to the UN Linda Thomas-Greenfield told reporters the prospect of a Russian invasion was “imminent,” a word the Biden administration had sought to avoid using in recent weeks for fear it sent the wrong message about Putin’s intentions.

“The evidence on the ground is that Russia is moving toward an imminent invasion,” the envoy told reporters. “This is a crucial moment.”

Thursday morning saw multiple fast-moving developments in the crisis, including shelling in the east of the country and the delivery of a Russian response to Western proposals on Ukraine and broader European security.

Both Ukrainian officials and Russia-backed separatists have blamed shelling in the village of Stanytsia Luhanska on each other, with Kiev calling it a “provocation.” 

Russia state-based media accused Ukraine of violating the 2015 Minsk Agreement cease-fire, a claim the Ukrainian Joint Forces Operation rejected.

The US Embassy in Ukraine backed the Kiev government’s account, tweeting: “Russia’s shelling of Stanytsia Luhanska in Ukrainian government-controlled territory in Donbas hit a kindergarten, injured two teachers, and knocked out power in the village.  The aggressor in Donbas is clear – Russia.”

UK Defence Secretary Ben Wallace warned at a NATO defense ministers meeting in Brussels that Putin could use the attack as pretext for an invasion. 

“It’s part of the playbook,” said Wallace, who warned of “activity on the ground in cyber, in forward or specialist forces, seeking to either do false flags or to create pretext. You’re definitely going to start seeing, we already are seeing, the raising of the rhetoric around alleged breaches.”

As if to emphasize the point, Wallace’s ministry tweeted out a two-minute “intelligence update” video detailing the state of play in Eastern Europe.

“Russia now has over half its ground combat power near the Ukrainian border, the largest since the fall of the Soviet Union,” the video’s narrator intoned. “The scale of this is far beyond anything needed for a large-scale training exercise.”

“If President Putin chooses conflict,” the ministry warned, “considerable numbers of civilians will die. Defence Intelligence suggests he would be willing to sustain thousands of casualties to get what he wants.”

The Ministry of Defence also revealed what it described as a “possible axis of invasion” by Russian forces, including a potential plan of attack targeting the Ukrainian capital of Kiev from positions in Belarus and western Russia. Another possible invasion route suggested Russian forces could advance on the city of Dnipro from the north and south in a pincer movement before driving west.

In the latest European diplomatic maneuvering, Ukraine, Poland and the UK announced Thursday that they had agreed to forge a three-way memorandum of cooperation on issues including cybersecurity, energy security and countering Russian disinformation.

“The UK and Poland will continue to provide Ukraine with support, standing in unity with Ukraine, in the face of ongoing Russian aggression, and fully committed to stand with [the] Ukrainian nation in its efforts aimed at defending Ukraine’s sovereignty, independence and territorial integrity within its internationally recognized borders,” read a statement from the British Foreign and Commonwealth Office. 

Meanwhile, the Kremlin repeated its demand that the US and NATO block Ukraine from joining the Atlantic alliance as well as roll back their military presence in Central and Eastern Europe. 

The demands were included in Russia’s long-awaited response to proposals from the US and NATO on Ukraine and Russia’s security – which rejected Moscow’s original demands that the alliance rule out further expansion last month.

At the same time, the US Embassy in Moscow revealed that Russia had expelled deputy chief of mission Bart Gorman – the outpost’s second-ranking official. The blog Diplopundit reported that Gorman and his family left Russia last week.

State Department spokesperson Ned Price described the Russian action as “unprovoked and we consider this an escalatory step and are considering our response.”

Thursday’s developments came just hours after a US official claimed late Wednesday that Russia had secretly added 7,000 troops near Ukraine’s border despite Putin claiming he would pull back forces earlier this week. 

In all, the US estimates Russia has massed approximately 150,000 troops around Ukrainian territory, along with heavy military equipment.

With reporting by Evan Simko-Bednarski