Ukrainian long-range drones struck an oil terminal in St. Petersburg and set it ablaze, President Volodymyr Zelenskyy said Wednesday, as the Russian city hosts an annual international economic forum that is a banner event for President Vladimir Putin. The drones flew more than 1,000 kilometers (600 miles) to hit the terminal, Zelenskyy said on social media. Clouds of black smoke rose over the city’s port after the attack. St. Petersburg is Russia’s second-largest city and is where Putin was born.Russian authorities said only that the Ukrainian drone strike targeted the city’s infrastructure, without providing further details. The airport of St. Petersburg briefly suspended flights overnight because of the attack. Authorities also cut off mobile internet services.

With the front line changing little as swarms of drones hinder battlefield movement, both sides have sought an edge by increasingly launching long-range strikes. The war that followed Russia’s invasion of its neighbor has now stretched into its fifth year, with no end in sight.

Ukraine’s drone successes embarrass PutinThe latest strikes are an embarrassment for Putin, weeks after he pruned back an annual Victory Day parade in Moscow due to fears of Ukrainian drone attacks.Putin is set to speak on Friday at the economic forum in St. Petersburg that the Kremlin views as a prestige event. The gathering has for decades been Russia’s leading event for attracting foreign capital. It is sometimes called Russia’s Davos, likening it to the World Economic Forum held in Davos, Switzerland.