A nighttime Russian ballistic missile attack targeted Kyiv early on Wednesday, injuring at least 53 people including eight children, officials said, as the Ukrainian president went to Scandinavia in pursuit of further international military support for his country after a trip to Washington secured no new pledges.

A series of loud explosions could be heard in Kyiv at 3 am as the city’s air defences were activated for the second time this week. Ukraine’s air force said Russia launched 10 ballistic missiles toward the capital and all were intercepted by air defences.

The attack on the capital underscored the continuing threat to Ukraine from the Kremlin’s missile arsenal in the 21-month war. Russia has in recent months been stockpiling its air-launched cruise missiles from its heavy bomber fleet, according to a recent assessment by the UK ministry of defence.

That may herald another heavy winter bombardment of Ukraine’s power grid. Moscow last year targeted energy infrastructure in an effort to deny Ukrainians heat, light and running water and break their fighting spirit.

As winter sets in and hinders troop movements, allowing little change along the front line, long-range air bombardment plays a growing role in the war.

Ukraine has dwindling supplies of air defence munitions and other ammunition.