A Russian fighter jet mistakenly bombed one of its own cities. Experts say that 'serious' cockpit errors are likely to blame.

A view shows the accident scene following a large blast in a street in the city of Belgorod, Russia, on April 20, 2023. Mayor of Belgorod City Valentin Demidov via Telegram/Handout via Reuters

• A Russian warplane mistakenly bombed one of its own border cities, on Thursday, officials said.
• An expert told Insider that the pilot may have confused the Russian city for a Ukrainian one.
• The expert said that the aircraft, an Su-34, has features to stop accidental release.

The accidental Russian bombing of a city close to the Ukrainian border on Thursday evening was likely down to "serious" errors made by the pilot, two military experts told Insider.

A Russian Su-34 dropped a bomb on the border city of Belgorod, around 25 miles north of the country's border with Ukraine, Russia's defense ministry said in a statement.

Footage posted on social media showed the blast striking near an intersection, sending cars flying in the air. At least two civilians were injured, officials said.

The ministry admitted that the bombing was caused by an "abnormal descent of aviation ammunition" from its own airmen.

Two military experts told Insider that it was strange for the Su-34 to be flying over a built-up city in the first place.

They attributed the accident either to a faulty bomb — or human error despite safeguards against it.

"If you are in a fighter jet, you have to pull the release toggle, and you have to press the button for the bomb to be discharged," Marina Mi ron, a Russian defense researcher at Kings College London, told Insider. "It's not like you accidentally press the button and it's falling. There is a sequence that needs to be performed. 

"So it is pretty likely that maybe the pilot might have mistaken Belgorod because it is so close to the border," she added. "Maybe he didn't look at the map properly. Maybe he lost orientation."

Justin Bronk, an airpower expert with the Royal United Services Institute (RUSI) think tank in London, told Insider that a fault with the plane itself would be surprising because the Su-34 " is one of Russia's more modern and sophisticated combat aircrafts."

"It is likely a case of either serious errors in cockpit procedures, or mechanical failure that either caused the weapon to separate from the aircraft prematurely, or if it was a glide-bomb to fail to glide once released and so fall well short of Ukrainian territory," he said. 

Russia's Ministry of Defense did not say what type of bomb it was, but some Russian commentators alleged it was a glide-bomb, the Associated Press reported.

Glide-bombs have longer range as they can fly some distance rather than fall straight down. They have been used more frequently by the Russian air force, but some say that they are prone to glitches, AP reported. 

However, both experts told Insider they are confused about why the plane was flying so close to a populated Russian city, with Miron noting "they could have easily avoided flying over Belgorod."  

The incident isn't the only high-profile error by the Russian air force.

In March a Russian Su-27 jet collided with a US drone over the Black Sea, a provocative act that US officials partly attributed to poor flying skills on the Russian side. In February an Su-25 crashed, also near Belgorod, killing the pilot.