KYIV, Ukraine — In the early days of the war in Ukraine, Russian troops seized control of Europe’s largest nuclear power plant after a fierce battle that included shrapnel hitting the containment structure of Reactor No. 1. The resulting fire was quickly extinguished, a thick wall prevented a breach, and in the ensuing five months the war, and global attention, moved on to new fronts, new outrages and new horrors.

The war has had no shortage of devastation and global consequence — shifting geopolitical alliances, hunger in Africa exacerbated by missing grain exports, massacres of Ukrainian civilians, mass migrations and enormous losses of Ukrainian and Russian troops. Yet the repeated shelling of the sprawling Zaporizhzhia Nuclear Power Plant in recent days has particularly roused widespread fears and outrage about the sheer folly and existential danger of turning Europe’s largest nuclear power plant into a theater of war.

President Volodymyr Zelensky of Ukraine, speaking late Thursday night to a nation that still bears the scars of nuclear catastrophe from the meltdown of the facility at Chernobyl in 1986, said the Kremlin was engaging in “unconcealed nuclear blackmail” and called the situation at the plant “one of the biggest crimes of the terrorist state.”

Neither side has interest in a meltdown, which in the worst case could lead to widespread releases of deadly radioactive material, contaminating territory stretching over hundreds of thousands of miles in whichever way the wind blew.

“The degree of infection of other territories of Ukraine and Europe, Russia and Belarus depends on the wind direction,” the State Agency for Exclusion Zone Management of Ukraine, which oversees the wasteland that still surrounds Chernobyl, said.

The plant’s reactors are designed to withstand a range of risks, from crashing planes to natural disasters. But direct hits by rockets and missiles may be another matter. Ukraine has so far resisted returning fire from the plant with American-provided advanced rocket systems, for fear of striking one of the six pressurized water reactors or highly radioactive waste in storage.

But experts expressed even more concern about damage from fires if a shell should hit a power transformer at one of the reactors. That could take the electric network offline, potentially causing a breakdown of the plant’s cooling system and leading to a catastrophic meltdown, said Edwin Lyman, a nuclear power expert at the Union of Concerned Scientists, a private group in Cambridge, Mass.

Each side blames the other for jeopardizing the safety of the plant.

Ukrainian officials have accused Russian forces of using the plant as a staging ground to launch missiles at the city of Nikopol on the western bank of the Dnipro River.

On Friday, days after at least 13 people were killed in shelling, more rockets fell, wounding three people, including a 12-year-old boy as well as damaging four high-rise buildings and numerous houses and shops, a regional official said. It was not clear whether the attacks overnight had come from the Zaporizhzhia plant.

The Ukrainians have also accused the Russians of hiding dozens of military vehicles with an unknown quantity of munitions on the premises of at least two reactors. The Russian nuclear agency, Rosatom, they say, is advising Russian forces about which parts of the plant site they can deliberately shell without posing a safety threat, with the idea of intimidating the world by creating a sense of danger (while blaming the Ukrainians).

Russian officials have said the Ukrainians are the ones trying to create a “dirty bomb” in the Russian-controlled territory by targeting the waste storage facility, and have claimed that Russian air defense systems had repelled Ukrainian drone and artillery attacks on the plant.

Rafael M. Grossi, the secretary general of the International Atomic Energy Agency, the U.N. nuclear watchdog, said that for now there was “no immediate threat” as a result of the recent shelling but warned that the assessment “could change at any moment.”

While under Russian control, the facility is operated by about 10,000 Ukrainian civilians, who are tasked with keeping the plant safely running in while facing harsh conditions, including intimidation and torture with electric shocks, according to Ukrainian officials.

“People are being abducted en masse,” Dmytro Orlov, the exiled mayor of the nearby city of Enerhodar, said during a meeting last month with officials from Energoatom the state agency that oversees Ukraine’s nuclear power plants. “The whereabouts of some of them are unknown. The rest are in very difficult conditions: They are being tortured and physically and morally abused.”

Ten employees are still missing, according to a Ukrainian energy official who could only discuss plant security matters on the condition of anonymity. That includes the head of the facility’s environmental protection service, Ihor Kvashnin, according to Energoatom.

The war shows no signs of abating, at the nuclear site or anywhere else along the southern and eastern front lines.

On Friday, a senior Ukrainian official suggested that the casualty toll from explosions at an air base in Crimea this week was far higher than previous estimates. That further contradicted a Russian claim of more limited damages. Images released by Planet Labs, a satellite imaging company, appear to show at least eight wrecked war planes and three blast craters in areas where planes were parked near the runways. Russia had used the site as a launching pad for military operations since its invasion of Ukraine began in late February.

The Ukrainian official, Anton Geraschenko, an adviser to the minister of internal affairs, said that 60 pilots and technicians had been killed and 100 people wounded when a series of explosions rocked the Saki field on Crimea’s western Black Sea coast on Tuesday. He said the conclusion was based on video evidence and intelligence data, but he offered no further details.

There has been no independent confirmation of the toll, and most experts have focused on assessing the damage to Russian military equipment. The Russian authorities have said that munitions stored at the site exploded, and denied that any aircraft were destroyed.

A senior Ukrainian official has said the blasts were an attack carried out with the help of partisans, resistance fighters who aid the Ukrainian military on Russian-occupied territory. But the government in Kyiv has been reluctant to specify how the explosions happened, or to elaborate on whether it was responsible.

Mr. Zelensky warned officials against disclosing details of attacks carried out by its forces, or from bragging.

“War is definitely not the time for vanity and loud statements,” he said in the remarks, which made no reference to the air base explosion. “The less concrete details you give about our defense plans, the better it will be for the implementation of those defense plans.”

Also on Friday, a U.N.-chartered bulk carrier, the Brave Commander, arrived in Ukraine to carry 23,000 metric tons of grain to famine-stricken parts of the Horn of Africa, the first to that region since the Russian invasion halted food exports six months ago. António Guterres, the secretary general of the United Nations, which brokered a deal last month between Ukraine and Russia allowing grain shipments, has called it “a beacon of relief.”

Instead the nuclear plant has emerged as a generator of global anxiety.

On Wednesday, foreign ministers from the Group of 7 major industrialized nations issued a statement from their meeting in Germany to demand that Russia withdraw its forces from Ukraine and immediately return control of the nuclear complex to Ukraine.

The statement blamed Russia’s military actions around the plant for “significantly raising the risk of a nuclear accident or incident,” endangering the entire region.

On Thursday, a State Department spokesman said the United States supported a demilitarized zone around the nuclear plant and called on Russia to cease military operations on its grounds or nearby.

Ukraine has sought to answer the constant shelling from the plant with precise counterattacks. On July 22, for instance, Ukraine’s military intelligence agency reported a strike with a kamikaze drone that blew up an antiaircraft installation and a Grad rocket launcher and that killed soldiers in a tent camp about 150 yards from a reactor.

Marc Santora reported from Kyiv and Jason Horowitz from Rome. William J. Broad contributed reporting from New York.