The air combat between Russian and Ukrainian forces intensified on Friday, with air raid sirens sounding in several Ukrainian cities, including the capital Kyiv, following multiple explosions, while Moscow claimed to have downed enemy drones in the Moscow, Kaluga and Kursk regions. Explosions were heard in the Ukrainian cities of Kyiv, Vinnytsia, and Khmelnytskyi, among others, Ukrainian media reported without providing further details. Meanwhile, Moscow Mayor Sergey Sobyanin said a Ukrainian drone was jammed near the city center, and Roman Starovoit, governor of Russia’s bordering Kursk region, said two Ukrainian drones were shot down as they approached the region. Moscow Vnukovo airport authorities announced flight rerouting after closing the airspace and suspending departures and landings owing to security concerns. Vnukovo is divided into two sections, one for civilian flights, both domestic and international, and the other for government flights, which only serve the Russian president and other officials. The airport has been targeted several times in recent months, never causing any damage but frequently disrupting air traffic. The authorities of Kaluga city, 162 kilometers (100 miles) from Moscow, have also closed airspace and canceled flight operations to ensure the safety of civil aircraft flights. Meanwhile, Ukrainian presidential advisor Mykhailo Podolyak told TV channel Ukrainian 24 that drone attacks on Russian territory will become “more frequent and effective.”