This week, Russian forces seized control of the defunct Chernobyl nuclear power plant, the site of the 1986 nuclear disaster. The disaster occurred after a reactor exploded and expelled massive amounts of radiation into the air and soil.
The surrounding areas after the explosion were evacuated, but radiation continued to spread far and wide. In the three decades since, there has been a reported rise in thyroid cancers, radiation-associated cataracts and other effects from radiation poisoning.
Now with activity occurring in the exclusion zone -- the 1,000-square-mile barren area around the plant which includes the nearby ghost town of Pripyat -- there are fears not of a potential second Chernobyl disaster but of radioactive material spreading from fighting in the area.
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The United Nations nuclear watchdog, the International Atomic Energy Agency, said Friday radiation measurements were slightly elevated, possibly because of tank movement on radiates soil. But the agency said levels remain low and within the exclusion zone's normal operational range -- making clear they don't pose any danger to the public.
But nuclear experts and Ukrainian government officials have expressed concern about potential health hazards from radioactive material spreading amid the fighting.
"Conventional war and nuclear power are not a good combination," Dr. Kate Brown, a professor of science, technology and society at the Massachusetts Institute of Technology, who has been studying Chernobyl for more than 15 years, told ABC News. "Nuclear power requires security, stability and peace. It's a tall order."
If any military activity sparks a fire, it could release radioactivity from the wooded areas of the exclusion zone, which could then spread, she said.
"There's been hotter, drier weather with climate change in Ukraine and elsewhere," said Brown. "From 2017 to 2020, they've had pretty serious forest fires in the contaminated areas, and they've released a great deal of radioactivity that's stored in the leaf litter, in pine needles, in the wood itself and, when those burn, they volatilize and become ash and smoke and can travel long distances."
If there is a fire, it could be difficult for firefighters or other emergency personnel to reach the area because they'll be busy treating civilian casualties, which could prolong the fire and release more contaminated material into the air, she said.
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Additionally, there is radioactive material that has been lodged underneath the soil in the contaminated zone for several years, Brown said.
Soldiers walking through or tanks driving through the area could also kick it up to the atmosphere and cause it to spread, experts say.
"War is a dirty endeavor," Dr. Ron Chesser, Professor Emeritus at Texas Tech University who has studied Chernobyl for more than 20 years, told ABC News. "It's going to throw up a lot of dust and dirt, and driving tanks and digging defenses and so forth is going to disturb the soil and release radiation and radioactive materials that would make it available for ingestion and in inhalation and potentially have some long-term negative impacts."
There are also concerns about whether the Russians soldiers are properly protecting themselves at the plant like workers would, Dr. Lydia Zablotska, a professor in the department of epidemiology and biostatistics at the University of California San Francisco School of Medicine, said.
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"I don't know whether Russian soldiers know anything about radiation, whether they have protective equipment, or whether they have a radiation deposition map of the area," Zablotska told ABC News." It is complete madness for them to go there."
Zablotska, a radiation expert, said she is also worried that military activities could disrupt the sarcophagus, the steel and concrete structure that covers the reactor that caused the 1986 disaster.
A hole being poked in the sarcophagus could cause radioactive contamination to leak into the environment, she said.
"It is necessary to keep the area around the sarcophagus and the area for radioactive waste storage safe and secure," Zablotska said. "No one should be allowed in the exclusion zone unless they are permitted to be there."
But some experts say they don't believe that Russia is trying to take possession of the nuclear inventory in Chernobyl and they are not worried about the plant being used as a nuclear weapon.
Chesser, the first American scientist given full access to the Chernobyl exclusion zone in 1992, says he believes the Russians' motives are two-fold.
"One is that they don't want that material to be used in some kind of offensive way against their troops in a dirty bomb," he said.
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A "dirty bomb" is defined by the United States Nuclear Regulatory Commission as a weapon that combined a "conventional explosive, such as dynamite, with radioactive material."
Ukraine has denied that it intends to develop a dirty bomb. In a tweet Saturday, Ukraine's Minister of Foreign Affairs Dmytro Kuleba said this was a false claim from Russia used to justify war.
"Russian propaganda has gone off the rails and speculates Ukraine might be preparing to drop a 'dirty bomb' on the Russian territory," he wrote. "This is a sick fake. Ukraine doesn't have nuclear weapons, doesn't conduct any work to create/acquire them. We are a responsible member of the [Non-Proliferation Treaty]."
Russian propaganda has gone off the rails and speculates Ukraine might be preparing to drop a ‘dirty bomb’ on the Russian territory. This is a sick fake. Ukraine doesn’t have nuclear weapons, doesn’t conduct any work to create/acquire them. We are a responsible member of the NPT.— Dmytro Kuleba (@DmytroKuleba) February 26, 2022
Chesser thinks another other reason Russians seized control of Chernobyl could be because of how symbolic it is to both Russians and Ukrainians.
"It's highly symbolic in that taking over the Chernobyl site is going to be a major news item even though that strategically it really has very little value for the Russian government," he said.