Sputnik/Aleksey Babushkin/Kremlin via REUTERS
- Russia said it is fighting a cross-border incursion by Ukraine in its Kursk region.
- Experts said Ukraine made it more than six miles into Russia, past significant defenses.
- Ukraine has not commented on the operation, which stands out from its usual tactics.
Ukraine managed to break through at least two Russian defensive lines and get past a stronghold in its unprecedented attacking on Russia's own territory, experts said.