Ukraine unleashed more than a hundred drones smuggled deep into Russia in what it called its most damaging attack yet.

Ukraine’s Security Service said it has struck at least 40 Russian bombers deep inside Russian territory in what would be one of the largest and most audacious attacks on Russian territory in the years long conflict.

With 41 military aircraft impacted, the Ukrainian drone attack was described by some commentators as Russia's "Pearl Harbor." The attack on Pearl Harbor in December 1941 was a surprise air raid by Japan on the U.S. during World War II. Kyiv's assault follows ground advances by Moscow troops in recent days in Ukraine's Sumy border region.