The Ukrainian security service, or SBU, has hit a S-400 Triumph air defence system in Russia’s Belgorod region, sources confirmed to following videos shared by Russians on social media.

It is at least the second successful attack on the system worth USD 1.2 billion, following a strike on Crimea last month.

"The videos posted by the Russians show about 20 explosions at the location of the Triumph and its radar system. At the same time, the neighbouring settlements lost power," the sources said.

Local residents reported explosions near Belgorod overnight on Wednesday.

The Russian defence ministry later said the air defences had allegedly intercepted and destroyed 31 Ukrainian drones over the Belgorod, Bryansk, and Kursk regions.

The S-400 is a Russian long- and medium-range anti-aircraft missile system designed to combat long-range reconnaissance aircraft, airborne missile systems, air command posts, strategic bombers, and (according to the creators) hypersonic cruise and ballistic missiles.

The radar has an instrumental range of up to 600 kilometres, and the 40N6E missiles can allegedly hit aerodynamic targets at a range of up to 380 kilometres, with an altitude limit of 35 kilometres.