Ukrainian drones on Wednesday struck energy and military targets in Saint Petersburg as Russia hosts a major economic forum.
Officials said a number of infrastructure sites were damaged, though no deaths were reported.
What do we know about the drone attacks on Saint Petersburg?
Regional governor Alexander Beglov said "several" facilities were hit on the outskirts of Russia's second-largest city.
Ukrainian officials said the attack aimed to disrupt the high-profile gathering, long known as "Russia's Davos," which President Vladimir Putin is expected to attend, as well as members of Germany's far-right Alternative for Germany party.
