A new strategy of attacks on logistical targets in Russian-held territory is having an impact, analysts say, symbolically as well as militarily.

KYIV, Ukraine — The Ukrainian military extended the fight deeper into Russian-controlled territory on Friday, as it sharpens a strategy of trying to degrade Moscow’s combat capabilities by striking ammunition depots and supply lines in the occupied Crimean Peninsula and other areas the Kremlin had long thought to be safe.

Crimea, a key staging ground for Russia’s invasion, has been firmly under Kremlin control since it was illegally annexed by Moscow in 2014. But it has been rocked by several recent attacks, some carried out by clandestine Ukrainian fighters operating behind enemy lines. Oleksiy Danilov, the head of Ukraine’s national security council, said on Friday that Kyiv would target sites in Crimea as part of a “step-by-step demilitarization of the peninsula with its subsequent de-occupation.”

Overnight into Friday, blasts hit at a military airfield outside Sevastopol, the largest city in Crimea and home to Russia’s Black Sea Fleet; the Russians later said the booms were the sound of successful antiaircraft fire. Loud bangs were also reported above the Kerch Strait bridge, the only land link connecting Russia to Crimea. There appeared to be no damage to the bridge, and Russia said that those explosions, too, were the result of antiaircraft fire.