CHERNOBYL, Ukraine. Ukrainian soldiers with Kalashnikov rifles on their backs patrol the quiet snow-covered forest, passing houses so long abandoned that creepers curl in broken windows.
Fields lie fallow, cities are empty, and the entire Chernobyl zone in northern Ukraine is still so radioactive that it seems to be the last place on Earth that anyone would want to conquer.
But while most of the attention around a potential Russian invasion is focused on the troop build-up and daily fighting in the east, the shortest route from Russia to the Ukrainian capital Kiev is from the north. And it passes through the isolated zone around the Chernobyl nuclear power plant, where a reactor meltdown in 1986 caused the worst nuclear disaster in history.
In one of the inconsistencies of the war, this makes Chernobyl a territory that Ukraine thinks it must defend, forcing its military to deploy security forces in a spooky and still radioactive forest where they have weapons and equipment to detect radiation exposure.
“It doesn’t matter if it is infected or no one lives here,” said Yury Shakhraichuk, Lieutenant Colonel of the Ukrainian Border Service. “This is our territory, our country, and we must protect it.”
Forces in the area known as the Chernobyl Exclusion Zone would not be strong enough to repel an invasion should it occur; this is mainly for detecting warning signs. “We collect information about the situation on the border” and pass it on to the Ukrainian special services,” Colonel Shakhraichuk said.
The concept of the Chernobyl exclusion zone, created by the Soviet authorities three decades ago, was to limit the death rate from an accident at a nuclear power plant through isolation. Radioactive particles left in the soil or stuck under the protective structure of a destroyed reactor, as long as they slowly decay, do not pose much of a danger to soldiers, as long as these soldiers do not linger in heavily irradiated areas. But the land must be abandoned, in some places for hundreds of years.
Two months ago, the government sent additional forces to the area because of heightened tensions with Russia and Belarus, a Kremlin ally that borders five miles from the burned-out reactor and to which Russia has recently deployed troops.
“How can it be?” said Ivan Kovalchuk, a Ukrainian firefighter who helped put out the fire at the station in the days after the accident, risking his life alongside Russians and people from all over the former Soviet Union. He said he was outraged that Russia could potentially threaten the zone militarily.
“Together we liquidated the accident,” Mr. Kovalchuk said. “The fact that they are doing this to us now just makes me feel sorry for the people in Ukraine,” he said.
Reactor No. 4 of the Chernobyl nuclear power plant exploded and burned out during a test on April 26, 1986, releasing about 400 times more radiation than the bombing of Hiroshima. Thirty people died immediately after the accident, most of them from radiation exposure; studies on long-term health effects have been largely inconclusive, but suggest thousands of people could eventually die from cancer.
Although the zone is uninhabitable, it attracts tourists for short visits, generating some income, and is seen in Ukraine as a lesson in recent history.
At the time of the accident, Ukraine was a Soviet republic, and initially the Soviet authorities tried to cover up the disaster. Not to arouse suspicion, a few days later they staged May Day parades in Ukraine, leading schoolchildren through swirling radioactive dust.
This callous attitude contributed to fueling anti-Soviet sentiment in Russia, Belarus and Ukraine, the most affected republics, and the accident is now seen as one of the reasons for the collapse of the Soviet Union five years later.
The Chernobyl zone covers about 1,000 square miles and follows the shortest direct route from the Belarusian border to Kiev. While this is not necessarily the most likely invasion route from the north, as it is marshy and densely forested, Ukraine does not rule it out.
Until last fall, the 700 miles of border between Ukraine and Belarus were barely guarded, especially in the exposed areas. About 90 miles of border separate the Ukrainian zone from a similarly isolated and irradiated area in Belarus called the Polessky State Radioecological Reserve.
The situation changed in November amid the migration crisis in Belarus and the buildup of troops in Russia.
The combination of these two events was ominous. Moscow began to draw up troops in such a way that plans were made to invade Ukraine through Belarus. Kiev also feared that Belarus might stage a provocation, for example, send migrants to the border with Ukraine, as Belarus did with Poland, and ignite the spark of war.
In response, Ukraine sent an additional 7,500 border guards to the Belarusian border. Colonel Shakhraichuk of the Border Guard said he could not disclose exactly how many went to Chernobyl. But fears of an invasion from Belarus have only intensified this week as Russia is sending troops and equipment there ahead of joint exercises with Belarus scheduled for February.
Only about a dozen soldiers were seen during a recent visit to the border area, but officials said others were patrolling elsewhere.
The Zone is a sad place to work. In the first days after the accident, about 91,000 people were evacuated in just a few hours.
Forests grew around their former homes. Looking out the windows, you can see clothes, shoes, dishes and other remnants of ordinary life lying around, covered with dust and lichen.
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In the largest city of Pripyat, now a ghost town, a propaganda poster still extols the virtues of civilian nuclear power. “Let the atom be a worker, not a soldier,” it says.
The risk of further spread of radiation as a result of the war seems minimal. But one site in the zone is particularly vulnerable: a new $1.7 billion stainless steel arch over the destroyed reactor, paid for largely by the US and about 30 other countries. It was completed in 2016 to prevent the spread of highly radioactive dust.
The city of Chernobyl is still partly inhabited by workers who live there during shifts. They maintain a containment over the damaged reactor, roads and other infrastructure.
“It’s bad, it’s scary,” Yelena Bofsunovskaya, a grocery store clerk, said of the possibility of hostilities near the destroyed reactor.
“We don’t know what will kill us first, the virus, radiation or war,” said Alexei Prishchepa, a worker standing at the store counter, shrugging his shoulders.
Mr. Prishchepa said he would prefer Ukraine to build defensive lines further south, giving the irradiated zone to anyone. “It’s a wasteland,” he said. “The crop will never grow here.”
Prior to the Russian build-up, the main security concern at Chernobyl was illegal mushroom picking and scrap metal collection, activities that could spread radiation outside the zone. Police also routinely detain thrill-seekers who enter illegally for sightseeing.
Most of the time, soldiers on patrol are at little to no radiation risk. But the long-lived particles remain, creating invisible, deadly hotspots in the forest. Some emit radiation levels thousands of times higher than normal. The soldiers mapped out routes to avoid these places, which had long been mapped by scientists.
However, while on patrol in the zone, soldiers must wear lanyards around their necks with devices that constantly monitor exposure; according to patrol protocols in the zone, if a serviceman stumbles upon a heavily irradiated area, he is removed from duty in order to avoid further exposure.
According to Colonel Shakhraichuk, so far none of the border guards sent to the zone in November have received high doses.
“There are very dangerous places that should be avoided,” said Major Alexei Vegera, a member of the Chernobyl police. The fighters of this force, who are used to working in the area, accompany the border guards on patrols.
“We try to be careful,” he said. But what can I say, I’m used to it.
Maria Varenikova made a report.