KYIV, Ukraine (AP) – A small explosive device carried by an improvised drone detonated Sunday at the headquarters of Russia’s Black Sea Fleet on the Crimean peninsula, injuring six people and canceling ceremonies there honoring the Russian navy, authorities said.
Meanwhile, one of Ukraine’s richest men, a grain merchant, was killed in what Ukrainian authorities said was a carefully targeted Russian missile attack on his home.
There was no immediate claim of responsibility for the drone explosion in the courtyard of the naval headquarters in the city of Sevastopol.  But the apparently improvised, small-scale nature of the attack raised the possibility that it was the work of Ukrainian rebels trying to drive out Russian forces.
A Russian lawmaker from Crimea, Olga Kovitides, told the Russian state news agency RIA-Novosti that the drone was launched from Sevastopol itself.  He said the incident was being treated as an act of terrorism, the news agency reported.
Crimean authorities have raised the terror threat level for the region to “yellow”, the second highest level.
Sevastopol, which was seized along with the rest of Crimea from Ukraine by Russia in 2014, is about 170 kilometers (100 miles) south of mainland Ukraine.  Russian forces control much of the mainland along the Black Sea.
The press service of the Black Sea Fleet said the drone appeared to be improvised.  He described the explosive device as “low-powered.”  Sevastopol Mayor Mikhail Razvozhaev said six people were injured.  Celebrations of the Russian Navy Day holiday were canceled in the city.
Ukraine’s navy and an adviser to President Volodymyr Zelenskyy said the reported drone strike highlighted the weakness of Russian air defenses.
“Did the invaders admit the weakness of their air defense system?  Or their weakness in front of the Crimean partisans?”  Oleksiy Arestovich said on Telegram.
If such an attack is possible from Ukraine, he said, “the destruction of the Crimean bridge in such situations no longer sounds unrealistic” – a reference to the span Russia built to connect its mainland with Crimea after the annexation .
Elsewhere in Ukraine, the mayor of the major port city of Mykolaiv, Vitaly Kim, said the bombing killed one of Ukraine’s richest men, Oleksiy Vadatursky, and his wife, Raisa.  Vadatursky headed a grain production and export business.
Another adviser to the president, Mykhailo Podolyak, said Vadatursky was specifically targeted.
“It was not an accident, but a well thought out and organized premeditated murder.  Vadatursky was one of the largest farmers in the country, a key figure in the region and a major employer.  That the exact hit of a missile was not only on a house, but on a specific wing, the bedroom, leaves no doubt about the targeting and adjustment of the strike,” he said.
Vadatursky’s agricultural business, Nibulon, includes a fleet of ships to ship grain abroad.
In the Sumy region of northern Ukraine, near the Russian border, shelling killed one person, the regional administration said.  Three people were also killed in attacks last day in the Donetsk region, which is partly under the control of Russian-backed separatist forces, regional governor Pavlo Kirilenko said.
Podolyak said on Twitter that images from the prison where at least 53 Ukrainian prisoners of war were killed in an explosion on Friday indicated that the blast came from the building in Olenivka, which is under Russian control.
Russian officials claimed the building was attacked by Ukraine with the aim of silencing the prisoners who might have been providing information on Ukrainian military operations.  Ukraine blamed Russia for the blast, saying it was done to cover up the torture and execution of prisoners.
Satellite photos taken before and after show that a small, square building in the middle of the prison complex was demolished, its roof in pieces.
Podolyak said those images and the lack of damage to adjacent structures showed the building was not attacked by air or artillery.  He argued that the evidence was consistent with a thermobaric bomb, a powerful device sometimes called a vacuum bomb, detonated inside.
The International Committee of the Red Cross requested an immediate visit to the prison to make sure the dozens of injured prisoners are being treated properly, but said Sunday that its request had not yet been granted.  He said denying access to the Red Cross would violate the Geneva Convention on the Rights of Prisoners.
Meanwhile, Zelensky said the war has significantly reduced the size of Ukraine’s grain harvest compared to previous years, but that Ukraine is working on ways to export what it has to avoid a global food crisis.
“Ukraine’s harvest this year risks being halved,” he said on Twitter.
Russia and Ukraine recently reached an agreement that would allow the release of millions of tons of grain held in Black Sea ports.  Officials said they expect shipments to begin soon.