Kyiv’s drones struck an oil terminal at St. Petersburg’s port on Wednesday, sending clouds of black smoke over the Baltic Sea city as President Vladimir Putin prepared to address an international economic forum meant to burnish Russia’s business credentials. President Volodymyr Zelenskyy said the attack, which flew more than 1,000 kilometers (600 miles), is part of a campaign to diminish Russia’s oil production — a key source of funding for Moscow’s war effort — and to disrupt weapon production.

Russian authorities confirmed a Ukrainian drone strike targeted the city’s infrastructure but did not provide further details. St. Petersburg’s airport briefly suspended flights overnight, and authorities cut off mobile internet services, according to reports. Russia’s Defense Ministry said air defenses had downed 354 Ukrainian drones across the country overnight.

The St. Petersburg International Economic Forum, where Putin is scheduled to speak Friday, is viewed by the Kremlin as a prestige event, although major Western investors and officials have stayed away since Russia invaded Ukraine in February 2022. Saudi Arabia is a special guest country this year and is due to send a large business delegation.

The strikes are an embarrassment for Putin, who weeks ago had to prune back the annual Victory Day parade in Moscow over fears of Ukrainian drone attacks. MSI previously reported that Ukraine launched a major drone attack on Moscow and the surrounding region in May, killing four and wounding a dozen, in one of the largest strikes on the capital area since the war began here.

Wednesday’s attack struck St. Petersburg on the heels of a massive Russian barrage against Ukraine. Russian forces on Tuesday launched a large-scale drone and missile attack on Kyiv and other cities, killing at least 22 civilians and wounding 138, according to Ukrainian authorities. Moscow fired 198 long-range drones at Ukraine overnight Wednesday, Ukraine’s air force said, with air defenses neutralizing 189.

Ukraine has repeatedly targeted oil facilities at the port of St. Petersburg and nearby ports since launching its long-range drone campaign deep into Russian territory.

In addition to the St. Petersburg strike, Zelenskyy said Ukrainian drones hit the Kronstadt naval base, a historic base for Russia’s Baltic Fleet, and a manufacturing plant involved in weapon production in Russia’s Tambov region about 600 kilometers (370 miles) from Ukraine.

In the Russia-controlled part of Ukraine’s Donetsk region, a Ukrainian strike hit a bus traveling from Moscow to Crimea, killing seven and injuring 11, according to the Kremlin-appointed head of Donetsk, Denis Pushilin.

In Russia’s Smolensk region, two firefighters were killed by a Ukrainian drone attack, according to regional Gov. Vasily Anokhin. He said two other firefighters and a local resident were injured.

Authorities in Ukraine’s northern Sumy region said that over the previous 24 hours one civilian was killed and 15 more were injured, including three children, by Russian strikes. In the southern Kherson region, Russian overnight shelling and drone strikes killed an 86-year-old woman and wounded five other people, according to regional authorities.

With front lines changing little as swarms of drones hinder battlefield movement, both sides have increasingly relied on long-range strikes to seek an advantage. The war has now stretched into its fifth year with no end in sight.