Some European countries have resurrected or expanded their compulsory military service after Moscow’s invasion of Ukraine — a once-unthinkable policy shift fueled by the notion that they’d have to respond quickly if the Russian bear trudges across their borders.

Many nations ended their drafts after the Soviet Union collapsed in 1991. But as the risk of a widening war rises, alarm bells have sounded in countries near the Russian border, including the smaller Scandinavian and Baltic states most likely to be threatened.

“We are coming to the realization that we may have to adjust the way we mobilize for war and adjust the way we produce military equipment and we recruit and train personnel,” said Robert Hamilton, head of Eurasia research at the Foreign Policy Research Institute and a former US Army officer, to CNN on Sunday.

“It is tragically true that here we are in 2024 and we are grappling with the questions of how to mobilize millions of people to be thrown into a meatgrinder of a war potentially,” Hamilton said.

“But this is where Russia has put us.”  

The tiny nation of Latvia — with its just under 2 million people wedged between Russia and the Baltic Sea — is the latest to reintroduce conscription, which it abolished in 2006.

As of Jan. 1, 2024, men must register for the draft as soon as they turn 18.

The country’s citizens pushed back at first, according to Arturs Pīlācis, a 20-year-old student. But that faded as the need to defend their homeland became clear, CNN said.

“There wasn’t really an option where we can stand by and think things will go on as they were before because of the unprovoked aggression in Ukraine,” he told the network.

In Norway — which already has mandatory conscription — elected officials presented in April a long-term plan to double the defense budget and draft 20,000 soldiers, employees and reservists to serve in the armed forces.

“We need a defense that is fit for purpose in the emerging security environment,” Prime Minister Jonas Gahr Støre said.

Some of the conscripted seem to agree.

“I am willing to fight for my country if need be because I believe in the values that the Norwegian society is built on, and I believe those values of inclusion and equality and democracy are worth fighting for,” said student Jens Bartnes, a 26-year-old who finished his military training about seven years ago.

Lithuania, another Baltic state with a long-simmering fear of Russian invasion, has seen similar changes since it reintroduced conscription in 2015, CNN said.

Not everyone there is fond of the draft, according to Paulius Vaitiekus, president of Lithuania’s National Students’ Union.

But there has been “a shift in the mindset of the youth towards being more active, although not necessarily through conscripting,” he said, adding that students have been sending supplies to the Ukrainian front to help the embattled nation fight off its Russian aggressor.

Other countries such as Finland, Norway and Sweden have small standing armies but also the ability to call up thousands — and sometimes hundreds of thousands — of already-trained volunteers at a moment’s notice.

The Finnish Defense Force, for example, only has about 13,000 active members. But it can activate nearly a million reservists — and 280,000 of those can respond immediately, CNN said.

That makes it a good example of how to mix a small professional army with a mammoth amount of civilian reinforcements, Hamilton said.

That model worked well against the Russians in the past, specifically when the country nearly fought the Soviet Union to a standstill during a series of savage wars that ended with the Moscow Armistice in 1944.

Germany has also sought to reinvigorate its military, which has not been a priority since the country’s defeat in World War II.

This year, the nation updated its plans to respond to a war in Europe. And last month, Defense Minister Boris Pistorius proposed a new voluntary military service so the country would be “ready for war by 2029.”

The North Atlantic Treaty Organization — a k a NATO — is also trying to up its game in response to the Russian threat.

“Since 2014, NATO has undergone the most significant transformation in our collective defense in a generation,” rep Farah Dakhlallah told CNN.

“We have put in place the most comprehensive defense plans since the Cold War, with currently more than 500,000 troops at high readiness.”

The alliance doesn’t tell its members whether to conscript citizens, Dakhlallah said. But about a third do, and others are now weighing it.

“The important thing is that allies continue to have capable armed forces to protect our territory and our populations,” Dakhlallah said.

Retired US Gen. Wesley Clark said Putin’s campaign of open war against Ukraine — with the goal of recreating the Soviet empire — should be a wake-up call.

“So we’ve now got a war in Europe that we never thought we would see again,” Clark, who also served as NATO’s Supreme Allied Commander Europe, told CNN.

“Whether this is a new Cold War or an emerging hot war is unclear,” he continued.

Still, “it’s a very imminent warning to NATO that we’ve got to rebuild our defenses.”