WARSAW, POLAND -- Two stories beneath a modern steel production plant on Warsaw's northern edge lies an untouched Cold War relic: a shelter containing gas masks, stretchers, first aid kits and other items meant to help civil defence leaders survive and guide rescue operations in case of nuclear attack or other disasters.

A map of Europe on a wall still shows the Soviet Union -- and no independent Ukraine. Old boots and jackets give off a musty odour. A military field switchboard warns: "Attention, your enemy is listening."

Until now, nobody had seriously considered that the rooms built in the 1950s -- and now maintained as a "historical curiosity" by the ArcelorMittal Warszawa plant, according to spokeswoman Ewa Karpinska -- might one day be used as a shelter again. But as Russia pounds Ukraine, with shelling around a nuclear power plant and repeated Russian threats to use a nuclear weapon, the Polish government ordered an inventory this month of the 62,000 air raid shelters in the country.

The war has triggered fears across Europe, and these are especially felt in countries like Poland and Romania that border Ukraine and would be highly vulnerable in case of a radiological disaster.

After the Polish government order, firefighters visited the steel plant's shelter last week and listed it in their registry. Warsaw's leaders said the city's subway and other underground shelters could hold all its 1.8 million residents and more in the case of an attack with conventional weapons.

The ArcelorMittal Warszawa plant's Karpinska is suddenly receiving inquiries about the shelter. Following Russian President Vladimir Putin's threats to carry out a tactical nuclear attack, "everyone is worried," she said. "I believe that he will not (stage a nuclear attack), that it would be completely crazy, but nobody really believed he would start this war."

Amid fighting around Ukraine's Zaporizhzhia nuclear plant, Poland also drew up a plan to give potassium iodide tablets to local fire stations, which would distribute them to the population if needed. There has been a rush elsewhere in Europe on potassium iodide -- which protects the thyroid gland in the neck in case of radiation exposure -- including in Finland where the government urged the population to buy them.

During the Cold War there were hundreds of thousands of shelters in Europe. Some dated from the buildup to World War II, while communist-era authorities also ordered that new residential and production facilities include underground shelters.

Finland, which borders Russia, along with Sweden and Denmark, have maintained their shelters in order. Finland, for instance, maintains shelters in cities and other densely populated areas capable of accommodating around two-thirds of the population. A few of them are designed to withstand detonation of a 100-kiloton nuclear bomb.

While some countries still maintain their Cold War underground shelters, after the collapse of the Soviet Union some were transformed into museums -- relics of an earlier age of nuclear fears that would offer no real protection today.

Bomb shelters were a key element in the former Yugoslavia's preparedness doctrine against a nuclear attack.

The most famous of all, in a mountainous area 60 kilometres from Sarajevo in Bosnia, is a vast underground fortress built to protect military and political leaders. Known then only to the Yugoslav president, four generals and a handful of soldiers who guarded it, the Konjic site was turned in 2010 into a modern art gallery.

"From the military-political and geopolitical standpoint, the global environment right now is unfortunately very similar to what it was like (during the Cold War), burdened by a very heavy sense of a looming war," said Selma Hadzihuseinovic, the representative of a government agency that manages the site.

She said the bunker could be returned to service in a new war, but with nuclear weapons having become far more powerful it would not be "as useful as it was meant to be when it was built."

In Romania, an enormous former salt mine, Salina Turda, now a tourist attraction, is on a government list of potential shelters.

Many urban dwellers also go past shelters every day without realizing it while riding subways in cities like Warsaw, Prague and Budapest.

"We measured how many people could fit in trains along the entire length of the metro, in metro stations and other underground spaces," said Michal Domaradzki, director of the security and crisis management for the city of Warsaw. "There is enough space for the entire population."

Attila Gulyas, president of the Hungarian capital's Urban Transport Workers' Union, has been involved in regular drills of the city's metro lines. He was trained to shelter thousands of people as chief of the Astoria station at Budapest's metro line 2.

"The system is still in place today, it works perfectly, it can be deployed in any emergency" Gulyas said. "Up to 220,000 people can be protected by the shelter system in the tunnels of metro lines 2 and 3."

But with Russia waging an energy war against Europe and power costs soaring, for many the chief worry is how to get through the winter.

Sorin Ionita, a commentator with the Expert Forum in Bucharest, Romania, said many consider a Russian nuclear strike improbable as it would not "bring a big military advantage to the Russians."

Still, Putin's threats add to a general sense of anxiety in a world in tumult.

Just days after the Russian invasion began, Czechs bought potassium iodide pills as a precaution of sorts against a nuclear attack. Experts say these might help in a nuclear plant disaster but not against a nuclear weapon.

Dana Drabova, the head of the State Office for Nuclear Safety said that in such a case, the anti-radiation pills would be "useless."

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Eldar Emric in Konjic, Bosnia; Karel Janicek in Prague; Bela Szandelszky in Budapest, Hungary; Jan M. Olsen in Copenhagen, Denmark; Jari Tanner in Helsinki, Finland; and Nicolae Dumitrache in Bucharest, Romania, contributed.