ODESA, Ukraine — After explosions tore through a Russian air base in Crimea on Tuesday, Russia’s Defense Ministry quickly played down the extent of the damage, saying a munitions blast had left no casualties and that no equipment had been destroyed.
Videos from the scene and an assessment by local officials, who declared a state of emergency, told a very different story, with at least one person killed, more than a dozen wounded and hundreds moved into shelters. More than 60 apartment buildings were damaged, along with 20 stores and other buildings, officials said. And on the grounds of the base, after the huge plumes of smoke cleared, the remains of a warplane could be seen apparently melted into the tarmac. Satellite imagery showed craters, burn marks and at least eight destroyed fighter jets.
The images and the report by local officials on Wednesday contradicted the Kremlin’s earlier account of what had happened in Crimea, a strategic peninsula in southern Ukraine that Russia illegally annexed in 2014, and suggested that the destruction there was far greater than acknowledged.
If Ukraine’s military and partisans were responsible for the blasts, as a senior Ukrainian official said, it would represent not only an embarrassment to President Vladimir V. Putin, who often celebrates the annexation, but also a challenge to his military’s ability to defend occupied territory that it has heavily fortified for years.
It is not yet clear whether the explosions will hinder Russia’s ability to defend against a developing counteroffensive by Ukrainian forces in the south. But the extensive damage to areas near the blast, along with the satellite imagery and video of the jet wreckage, suggests significant destruction to military assets that will be crucial as Russia tries to hang on to territories seized in the early days of the war.
The base is home to fighter aircraft and helicopters that Ukrainian officials say have been employed to deadly effect in the battle for Ukraine’s Black Sea coastal region. Ukraine’s military intelligence service has named several dozen pilots from the base it has accused of carrying out attacks on civilian areas.
Damage to the air base itself was difficult to assess on Wednesday. One video that emerged in the aftermath, verified by The New York Times, showed the charred nose cone of a fighter jet, its fuselage a black, shapeless mass.
Russia’s Defense Ministry said in a statement that the episode was caused by the explosion of stockpiled ordnance for warplanes at the base. The statement did not mention Ukraine or its military.
Satellite imagery, collected by the company Planet Labs and reviewed by The New York Times, challenged Russia’s account of the damage. The images, one taken hours before the explosions and one taken a day after, did not show the haphazard debris of a single blast, but rather what appeared to be three large craters from detonations.
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The imagery showed at least eight destroyed warplanes, both Su-30 and Su-24 fighter jets, all parked on the air base’s tarmac. Two buildings near the aircraft were completely destroyed as well, with damage and large burn marks observable elsewhere at the military base.
Other parts of the air base appeared intact, including several helicopters and a large ammunition depot.
Local officials, scrambling to explain and cope with the destruction, offered more detail about what had happened to the base, on Crimea’s western coast. The peninsula’s Kremlin-installed leader, Sergei Aksyonov, said on Wednesday that 252 people had been moved to shelters because of damage to homes. At least 62 apartment buildings and 20 commercial structures had been damaged in the blast, he said on Telegram, and officials were still cataloging damage to private homes.
Ukraine has not officially taken responsibly for the explosions, which startled beachgoers at a nearby Black Sea resort. But a senior Ukrainian military official said on Wednesday that Ukraine’s special forces — along with local resistance fighters loyal to the government in Kyiv — were behind the blast.
Speaking on the condition of anonymity to discuss delicate military matters, the senior official would not disclose the type of weapon used in the attack, saying only that “a device exclusively of Ukrainian manufacture was used.”
It was unclear what Ukraine would have used to cause the explosions. Ukraine possesses few weapons that can reach the peninsula, aside from aircraft that would risk being shot down immediately by Russia’s heavy air defenses. The air base, near the city of Novofedorivka, is about 200 miles from the nearest Ukrainian military position, reducing the likelihood that a missile strike was responsible.
An attack on a target in Crimea, which Russia has transformed over eight years of occupation into a bristling military hub, would also represent an expansion of Ukraine’s military reach since the invasion began in February. Although fighting has raged for weeks in southern Ukraine, including near Europe’s largest nuclear plant, Crimea’s distance and defenses have kept it far from Ukrainian attacks.
Videos reviewed and verified by The New York Times showed that a plume of smoke was rising from the air base just before at least three explosions: two in quick succession and a third a few moments later. It is unclear from the videos what caused the blasts.
The senior Ukrainian official would not disclose whether local resistance forces, known as partisans, carried out the attack or assisted Ukrainian military units in targeting the base, as has sometimes occurred in other Russia-occupied territories.
To reach targets deep behind enemy lines, Ukraine has increasingly turned to guerrillas in those territories, officials said. Partisans have, for instance, helped Ukrainian forces target Russian bases and ammunition depots in the Kherson region, Ukrainian officials say.
Ukraine’s military and its partisan allies, often acting in coordination, have managed to attack Russian targets in occupied territory far from the front. Russia has also had attacks within its own borders, including a helicopter assault on a fuel depot and fires at another fuel depot — both sites relatively close to Ukrainian territory.
Ukrainian officials have hinted at involvement in those strikes, but not made public admissions of responsibility. On Tuesday, Ukraine’s Defense Ministry said it could not “determine the cause of the explosion” in Crimea, and suggested that personnel at the base adhere to no-smoking regulations.
Russia has sought to stamp out resistance in occupied areas, using fear and indoctrination to force Ukrainians into adopting Russian documents, currency and television. In towns and cities in Kherson, the Russian-backed authorities have arrested hundreds of people and set the stage for referendums on unifying with Russia — like the one held in Crimea in 2014, denounced as illegitimate by Ukraine and the West.
Ukraine has pushed to retake territory in the south in recent weeks, but as fighting has intensified so have fears about the nuclear facility in the region, the Zaporizhzhia Nuclear Power Plant, the largest in Europe.
Russian forces have used the facility for weeks as a base to launch attacks, knowing that it is extremely difficult for Ukraine to return fire without threatening the plant’s reactors, according to the Ukrainian authorities and independent analysts.
Nevertheless, fighting appears to be escalating around the facility. Overnight, Russian forces fired Grad missiles at the nearby town of Nikopol from across the Dnipro River, killing at least 13 civilians and wounding 11 others, a Ukrainian military official in the region, Valentyn Reznichenko, said on Telegram on Wednesday.
It was not clear whether the overnight attack had come from the grounds of the nuclear plant. On Saturday, rocket fire struck a dry spent-fuel storage facility at the plant itself. Ukraine and Russia blamed each other for the episode, which prompted the head of the United Nations’ nuclear watchdog, Rafael Mariano Grossi, to express “grave concern” over the fighting.
Based on information provided by Ukraine, Mr. Grossi said on Tuesday that there was no immediate threat to nuclear safety as a result of Saturday’s incident. He again called for a team of U.N. nuclear experts to be allowed to go to the plant as soon as possible to help stabilize the situation.
Michael Schwirtz reported from Odesa, Ukraine, and Alan Yuhas from New York. Matthew Mpoke Bigg contributed reporting from London and Christiaan Triebert from New York.