Ukraine launched a drone barrage at St. Petersburg on Saturday, the final day of a major investment forum, hours after President Vladimir Putin spoke there and refused a proposal for talks with Kyiv.

The strikes on the city and the surrounding region set a defense ministry facility ablaze and disrupted operations at Russia’s second-largest commercial airport for several hours.

Russian air defense shot down 144 drones over the Leningrad region, Governor Alexander Drozdenko said in post on Telegram, describing it as an unprecedented assault. A fire broke out at a defense ministry site in the Lomonosovsky district, prompting a partial evacuation of nearby residents.

Kronstadt, the naval base on Kotlin Island, west of the city, was briefly closed to traffic, the district administration said.

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