On Sunday, Russian missiles struck the southern Ukrainian port city of Mykolaiv, killing the owner of a major grain exporter, while a drone attack on Russia's Black Sea military station was conducted from within the city in what a Russian politician describes as a "terrorist act."

Oleksiy Vadatursky, founder and owner of agribusiness enterprise Nibulon, and his wife died at their house as a result of the missile attack, according to a Telegram message from the governor of Mykolaiv, Vitaliy Kim.

The death of grain tycoon Vadatursky was regarded by Ukrainian President Volodymyr Zelenskiy as "a great loss for all of Ukraine."

The mayor of Mykolaiv, Oleksandr Senkevych, described the more than a dozen  missile strikes as perhaps "the most powerful" on the city in five months of war, with at least three people injured.

He claimed that attacks had resumed, but that there was no information on casualties or damage, Sunday evening.

An explosion injured five Russian navy personnel after a supposed drone flew into the courtyard of Russia's Black Sea fleet, according to the Crimean port city's mayor, Mikhail Razvozhayev.

However, Olga Kovitidi, a member of Russia's upper house of parliament, told the Russian RIA news agency that the attack was unquestionably carried out from within Sevastopol.

President Vladimir Putin commemorated Russia's Navy Day by stating that the navy would receive "formidable" hypersonic Zircon cruise missiles in the following months. The rockets may fly nine times faster than sound, evading air defenses.

The war in Ukraine was not included in the speech of the Russian leader after signing a new navy doctrine that depicted the United States as Russia's primary adversary and outlined Russia's global maritime goals for key regions such as the Arctic and the Black Sea.

Forbes estimates Vadatursky's net worth in 2021 to be $430 million, making him one of the wealthiest Ukrainians. According to Zelenskiy, the businessman has been constructing a sophisticated grain market with a network of transhipment facilities and elevators.

The governor of Sumy, Dmytro Zhyvjtsky, stated on his Telegram channel that Russian forces bombarded the city's northern border seven times, launching more than 90 separate attacks. 

Meanwhile, Kharkiv, the second largest city in Ukraine, was attacked by Russian missiles again, according to the city's mayor, Ihor Terekhov. He said three Russian S-300 missiles had destroyed the school's main building.