Inside, in what is normally a sports hall, hundreds of people are sleeping overnight on trestle beds.

More than 2,000 people including volunteers and students are taking part in the biggest civil defense exercise in Europe since the end of World War II. In the scenario, critical infrastructure in the central Finnish city of Kuopio, including power and water, has been disrupted by cyberattacks and there’s the threat of missile strikes from Finland’s neighbor, Russia.

The goal is for local authorities and ordinary people to rehearse what they would do if they came under attack for real.

But while underground bunkers and shelters may offer some protection from missiles, they are no defense against the campaign of sabotage and disruption that Western officials say Russia is carrying out across Europe. That has involved setting fires, attacking water facilities and power stations, and sending drones for sabotage into European Union airspace.

Finland’s border with Russia stretches more than 830 miles (1,300 kilometers) from the Baltic Sea up to the Arctic Circle. In 2024, along with Sweden, Finland joined NATO, following Russian President Vladimir Putin’s full-scale invasion of Ukraine. Until then, Finns were prepared to defend themselves against Russia largely alone.

Finland looks to Ukraine for lessons

Finland’s defense, said retired Army Colonel Asko Muhonen, relies not only on the military but on the “mindset” of ordinary Finns who are ready to take responsibility for their country’s security.

Muhonen, who organized the exercise in Kuopio, said that comes partly from the system of conscription which continued in Finland, even after the collapse of the Soviet Union.

Not everyone is happy about doing national service but “it’s our duty to serve and protect this country like people have before us. That’s why we have our independence,” said Jyry Pietikainen, 23, a conscript who was taught how to run the Kuopio shelter overnight.

Finland also needs to learn lessons from Ukraine, Muhonen said.

While the biggest shelter in Kuopio can fit 7,000 people, Ukrainians sometimes only have a few minutes to run to a subway station or underground parking lot. That means people need a shelter they can reach easily that offers some form of protection — not necessarily one that can withstand a nuclear attack, he said.

Dmytro Untila, 20, a Ukrainian student at the university in Kuopio, was at home in Odesa when Russian missiles struck his city on Feb. 24, 2022, the first day of the war. He sheltered in the entrance hall of his building because he didn’t have anywhere else to go, he said.

Training for such a situation would have definitely helped in Ukraine, he said, “because nobody knew this could happen.”

The biggest threat to energy infrastructure in the Kuopio region is heavy snowfall, storms and bad weather, said Juha Räsänen, CEO at the Savon Voima electricity company.

But since the invasion of Ukraine, and the company’s decision to stop buying Russian biofuel, the number of cyberattacks against the network has significantly increased, Räsänen said.

Last year, engineers also found at least 10 stickers placed on particularly vulnerable parts of the energy network infrastructure. Other energy companies in Finland have also found them and don’t know where they came from, he said.

“If there was an explosion at that point, it could destroy a whole dam,” Räsänen said. Drones have also been spotted over power lines but those responsible have not been identified, he said.

It is not possible to guard against all threats, Räsänen said, which is why it’s important people are prepared to look after themselves without help for at least 72 hours — if the power supply goes out, or if water becomes undrinkable.

The Finnish Security and Intelligence Service said it investigated “a wide range of observations” and found nothing of concern.

Since 2022, people have been more vigilant because of the security situation and therefore have reported things like reflective stickers related to land survey works, it said in a statement. Drone sightings, it said, have “largely been explained by everyday occurrences.”

“Small things are happening all the time,” including Russian jamming of GPS signals, said Vuokko Lahtinen, 32, who was visiting a sauna in Kuopio.

For that reason, “the best defense of Finland is to make it not worth attacking,” she said.

That relies on the country’s military and defense forces but also Finnish people who feel like “we have something we want to fight for,” she said.

In Finland, she said, there is a “general feeling of responsibility,” which has grown out of local community groups and even initiatives such as recycling.

“On a very simple daily level, if you do things that matter, then it has a butterfly-wing effect,” Lahtinen said.

Finland fought several wars with the Soviet Union

In its wars with the Soviet Union, Finland lost around 11% of its territory, and more than 400,000 people, around 12% of the population, fled their homes from an area that is now in western Russia.

At Kuopio’s veterans’ museum, Risto Mönkkönen, 95, showed AP a piece of paper on which he had written down the dates the city was bombed and who died.

“I cannot forget it,” he said explaining how, as a child, he and his father ran into a shelter just as a bomb hit, killing five of his father’s friends.

Pirkko Naukkarinen, 102, recalled how, aged 16, she worked in a field kitchen by the front lines, sometimes sharing dugouts with soldiers and diving for cover in ditches as the Soviet air force attacked the retreating Finnish army.

Aili Toivanen, 92, told AP she was forced to leave her home twice over the various wars. Both times, her family was told by Finnish soldiers that they had one hour to pack their belongings.

The first time, she looked back and saw her home burning — set on fire by Finnish soldiers who did not want to leave anything behind, she said. The second time, she said, the Soviet air force bombed the family’s departing train and they jumped out, hiding in ditches before they took refuge in Kuopio.

When Putin invaded Ukraine in 2022, she said, with tears in her eyes, that she worried she would have to leave her home for a third time.

Finns feel their country is worth fighting for

At the shelter in Kuopio, thousands of people filed in, including schoolchildren and university students.

“Kids would need to know this, because they might have to do something alone. The adults can’t always help,” said Amanda Hill, 11, whose school studied in the shelter for the day.

Sitting on the floor of the shelter with his fellow conscripts, Pietikainen explained why it’s not crazy to practice what happens in a crisis.

“We’re Finns, so we’re kind of pessimistic about life in a way,” but history shows what can happen with Russia, he said.

When it comes to the threats from Moscow, Muhonen said, “don’t believe what they say but observe what they do.”