Intercontinental ballistic missiles (ICBMs) — the kind that can carry nuclear warheads — are usually only seen in military parades and during remote pre-planned tests.
So when Vladimir Putin's Ministry of Defence posted a video of a column of Russian ICBMs casually driving down a highway with Russian flags waving during this crisis, it raised heart rates as much as eyebrows.
Hours later came the Russian President's address to his nation's military.
"I'm ordering the Defence Minister and chief of the general staff to switch the Russian army's deterrent forces onto a high alert mode of combat stand-by duty," he said.
It is important to note the video of the ICBMs on the highway did say they were heading to a military parade, but Mr Putin's three nuclear warnings in as many weeks have sent chills down the spines of military analysts.
"Putin has gone over a threshold that was not crossed during the Cold War," said Michael Kimmage, a former adviser on Ukraine and Russia for the US State Department during the Obama administration.
"The Cold-War messaging from the Soviet Union, from the United States, about nuclear weapons was far more disciplined than what Putin has been doing in the last couple of weeks.
"He's made one just blatant threat about using nuclear weapons if the situation doesn't go his way.
"Obviously, you don't want to get into a war of words, or a kind of tit for tat, or some kind of escalatory spiral politically with Putin. But I think you can't let that go on answered."
French Foreign Minister Jean-Yves Le Drian did respond. "Vladimir Putin must also understand that the Atlantic Alliance is a nuclear alliance," he told French TV.
"The French didn't find the perfect recipe," Professor Kimmage said. "But to go back and forth, and keep on a level with Putin, that to me makes perfect sense at the moment.
"If Putin's going to bluster in that manner, it's not that you bluster in return, but you remind him that the costs of even this kind of threatening are going to go both ways.
"If he's going to break the rules, there will be certain kinds of consequences."
At this time of international crisis, Russia and the US must keep lines of communication open, he said.
"What has happened in the last few weeks has left very few channels of communication between Washington and Moscow," Professor Kimmage said.
"That's not entirely without precedent, but it's important.
"The Soviet Union and the US only avoided nuclear war during the Cuban Missile Crisis by communicating."
A new domino effect is playing out and it does not bode well.
Professor Kimmage spelled it out like this: "Putin's repeated messaging about using nuclear weapons comes at a time when there's almost complete mistrust among Western leaders and the Russian leader," he said.
"That combined with fewer and fewer channels of communication, and escalating sanctions and military commitment from the West to Ukraine, [adds the pressure on Russia] while the Russian attack falters.
"It doesn't mean Putin will use nuclear weapons of course — I doubt he's suicidal — but at the moment this is a crisis with no exit."
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