By claiming captured Ukrainian territory as Russian and vowing to use "full protection" to defend it, President Vladimir Putin has dramatically upped the stakes in the Ukraine War and set his country on a collision course with the West for which he appears to have left no off-ramp.
"This is a huge escalation," said Alissa de Carbonnel, a London-based analyst and long-time Russia watcher with Crisis Group.
"He's trying to draw new red lines now with this annexation and trying to extend the so-called 'nuclear umbrella,' and in one stroke change the whole map."
Russia's moves on annexation, and the rigged referendums that preceded them, have been widely denounced by Western nations as illegitimate and meaningless.
By folding the Ukrainian territories into Russia, at least from the point of view of the Kremlin, its military is now justified in using nuclear weapons to defend them.
"I want the Kyiv regime and their sponsors in the West to hear me, to heed me," said Putin.
Not-so-veiled nuclear threats
Putin's veiled nuclear warnings and his move to incorporate the conquered lands into the Russian Federation follow a series of military and diplomatic embarrassment that have left the Russian leader in a precarious position.
At a recent summit in Uzbekistan, India's Prime Minister rebuked Putin for continuing with the war. Putin was also forced to publicly acknowledge that China's leadership has concerns as well.
An even bigger factor affecting the Kremlin's strategy has been Russia's poor battlefield performance.
Ukraine's military has scored a series of dramatic successes, allowing its forces to recapture thousands of square kilometres of territory in the Kharkiv area and rout the disorganised Russian troops defending it.
Even as Putin was speaking at the Kremlin, Ukrainian troops were close to encircling the Donbas city of Lyman, in the Donetsk region, and possibly cutting off or capturing thousands of Russian soldiers.
The annexation, along with Putin's not-so-veiled nuclear threats, are an attempt to compel Ukraine to cut a deal with Russia and for the West to stop supplying Ukraine's military with effective weaponry.
"It's certainly an attempt to coerce, threaten and intimidate," said de Carbonnel.
Putin returned to the nuclear threat again in his Friday speech.
"The United States is the only country in the world that has used nuclear weapons twice, destroying the cities of Hiroshima and Nagasaki in Japan," said Putin.
"And they created a precedent," he said, as if those events at the end of the Second World War over 77 years ago somehow justified Russia to employ a similar weapon now.
How the West responds
Putin, who has led Russia for 22 years as president and prime minister, has cultivated a tough-guy image as an authoritarian leader who doesn't back down and doesn't compromise, especially not with the leaders of Ukraine, a country he believes does not have the right to exist.
In his speech before the Kremlin elite on Friday, Putin, as he has often done in the past, characterized Ukraine as a mistake of history — an entity created by accident when the Soviet Union collapsed in 1991 and Ukrainians were separated from what he says is their rightful home in Russia.
"A criminal policy was pursued to cultivate hatred for Russia," he said, accusing a succession of pro-western Ukrainian leaders of giving him "no choice" but to launch what the Kremlin calls a "special military operation" — or, a war, by any other name.
U.S. leaders are saying publicly that they believe the chance of Putin resorting to a nuclear weapon remains small.
On Friday, U.S. National Security Advisor Jake Sullivan repeated that American officials have not detected any evidence that Russia has begun to prepare its extensive nuclear arsenal.
Who makes the next move is unclear.
Ukraine's government says it will ignore Putin's annexation. Western governments have taken the same view and on Thursday the United States announced another $12 billion in military and economic aid to help Ukraine keep fighting.
Ukraine's army continues to make progress reclaiming territory in the Donbas area and there is also intense combat in the southern Kherson region.
"I think we [have] actually crossed the point where this is negotiable in any way," said Nina Khrushcheva, professor of International Affairs at The New School in New York.
"I think we are now in a new level of confrontation."
Khrushcheva, who is currently in Moscow, is the great granddaughter of Nikita Khrushchev who was the leader of the Soviet Union during the Cuban Missile Crisis in 1962, the last time nuclear tensions were so high.
Back then, Khrushcheva says it was clear neither the U.S. President John F. Kennedy nor Khrushchev wanted to use nuclear weapons and there was a mutual desire to avoid a war.
But now, with Vladimir Putin, she says she's not so sure.
"I think that all sides are determined not to lose and not to show weakness. I think we are getting to a very dangerous point."
Critical infrastructure at stake
Russia may have other means of gaining leverage against Ukraine and its Western backers, aside from nuclear coercion.
This discovery this week of major leaks in several natural gas pipelines under the Baltic Sea have Western governments eyeing Russia, but so far holding off on officially accusing the Putin regime of sabotage.
Putin, in his Friday speech, blamed the United States, saying it was all part of the bigger plot to hurt Russia, but he offered no evidence.
European investigators have said the pipeline damage was on such a large scale that it had to be the work of a state actor, and they don't believe any NATO members were responsible.
In the aftermath, Norway and Denmark have announced they are tightening the monitoring of their critical infrastructure.
"It does signal that critical infrastructure is a threat," said de Carbonnel of the Crisis Group.
"We have also seen this with cyber attacks. Russia has been willing, and indeed able, in a lot of instances to reach for many different methods of leverage."
WATCH | European leaders say Nord Stream damage was intentional:Russia has denied responsibility for damage to two pipelines that carry Russian gas to Europe. Nord Stream 1 and 2 carried gas to Germany, but were shut down in August.
Putin's annexation moves also leave a key question unclear: where exactly Russia views the boundaries of the four Ukrainian territories that it now claims are part of the Russian Federation.
While most of Luhansk Oblast is under Russian control, the other regions of Kherson, Donetsk and Zaporizhzhia are highly contested and filled with Ukrainian troops.
That adds to the uncertainty of what Russia would consider an attack on its territory.
Putin annexed the Crimea Peninsula after Russia's military took over the Ukrainian territory in 2014 but after a series of Ukrainian air and drone attacks on targets earlier in the war, there was no discernable Russian response.
Khrushcheva, the international affairs professor, said even if Putin is eventually overthrown and replaced with another leader, his move to annex the Ukrainian territories will make it much harder to come to a peace agreement with Ukraine.
"As we know, it's very difficult to give up territories because the public becomes very attached to them. Putin did future Russia a horrible disservice because it's going to be very difficult to unravel."