Ukraine said its military had launched a counteroffensive in its capital, Kyiv, and other key cities, as President Volodymyr Zelensky urged the U.S. Congress to provide more weapons and increase economic pressure on Russia.

The thump of distant shelling echoed through the center of Kyiv overnight, while Ukrainian forces appeared to counterattack in the outlying towns of Irpin, Bucha and Hostomel, which have been severely damaged in weeks of street fighting and artillery exchanges. The city and the surrounding region were under an all-day curfew Wednesday.

Ukrainian forces also said they pressed an offensive south and east of the southern port of Mykolaiv, moving in the direction of Kherson, the only Ukrainian regional capital occupied by Russia since the war began Feb. 24. Ukraine said it carried out an airstrike on the Kherson airport, which is now a Russian air base, and satellite imagery of the tarmac showed seven destroyed or damaged Russian helicopters, some of them engulfed in flames. Kyiv also said it shot down two Russian Su-30SM jets over the Black Sea off Odessa.