Ukrainian forces have been stepping up their offensive in recent weeks. The focus is Crimea, which Russia unilaterally annexed nine years ago. NHK asked a senior Ukrainian government official why its forces are concentrating their efforts on the peninsula.

Ukraine's defense ministry said on Friday the country's forces had successfully struck the headquarters of the Russian Black Sea Fleet.
Ukraine is believed to be staging more attacks on Saturday. The country's media reported a fire near a facility of the naval fleet.

A US think tank has released a map showing targets in Crimea struck by Ukraine in the last three months.
An attack on September 13th reportedly damaged a submarine and a landing ship that were undergoing repairs in Sevastopol.
Ukraine's defense ministry said earlier this month it had retaken control of gas drilling platforms in the Black Sea.
It said the facilities were equipped with ship-tracking radar that Russia used for military surveillance.

Since Russia annexed the region in 2014, Crimea has served as a strategic hub for the country as the home port of the Black Sea Fleet. It is also known as an area that holds symbolic value to President Vladimir Putin.

Ukraine's presidential advisor Mykhailo Podolyak told NHK that 80 percent of supplies to the Russian frontline units are delivered via Crimea. Podolyak says attacks on the region have three objectives. One is to destroy Russian air defenses. Another is to sever Russia's supply routes, and the third is to recapture control over the Black Sea, which is vital for Ukrainian agricultural shipments. Podolyak said, "Russia will undoubtedly face serious political problems in the country if Crimea's liberation begins."
Russia may consider Ukraine's recent attempt to recapture Crimea a red line. Back in March, Putin's close aide referred to the possibility of using nuclear weapons, apparently to warn Ukraine against launching a major offensive to retake the peninsula.
But the senior Ukrainian official has stressed that the attacks on Crimea will continue.