An oil storage depot is on fire in a Russian city just north of Ukraine after what the local governor said was an attack by two Ukrainian helicopters.
A video shared on Twitter shows a blaze near apartment blocks in Belgorod, some 40km (25 miles) from the border.
Some clips appear to show rockets hitting the oil depot.
However, Ukrainian aircraft have not struck targets in Russia previously. Governor Vyacheslav Gladkov’s claim was not confirmed by Ukrainian officials.
Belgorod, a city of 370,000, lies just north of Ukraine’s second city Kharkiv, which has been heavily shelled by Russian artillery and remains surrounded by Russian forces.
Governor Gladkov said in a Telegram message “there was a fire at the oil depot because of an air strike carried out by two Ukrainian army helicopters, which entered Russian territory at low altitude”. “Nobody was killed,” he added.
He said emergency workers were trying to contain the fire as quickly as possible and that there was “no threat” to residents. The emergencies ministry posted video of the blaze on Telegram.
Interfax news agency reported that residents nearby were evacuated and two people were injured at the depot. It said eight fuel tanks were on fire and nearly 200 firefighters were on the scene. The depot is run by Russian state oil firm Rosneft.
On 29 March several explosions were reported at an ammunition depot near Belgorod.
Ukrainian helicopter pilots have plenty of experience of flying low and fast to avoid being detected by military radar and air defence systems.
But flying at night, well into Russian territory, to launch an attack on an enemy fuel depot would have required extraordinary bravery – as well as finely-honed flying skills.
Low-flying helicopters are still vulnerable to short-range air defence systems. Flying at night would have lessened that risk, but heightened the danger of hitting an object near the ground.
The Mi-24, or Hind helicopter, is known as the “flying tank”. Its rockets would have been the weapon deployed to target the oil depot in Belgorod, Russia. If confirmed – and Ukraine is yet to claim responsibility for the attack – it would be the first known Ukrainian strike on Russian territory, bringing the war home to Russia.
This attack alone will not dramatically alter the battle. But it could show Ukraine has managed to keep its air force functioning, and give a huge boost to the morale of Ukraine’s military.