What was stored at the Russian arms depot in Tver region struck by Ukraine's drones?

A Ukrainian drone attack on a significant Russian weapons stockpile in the Tver region in the early hours of Wednesday might be the Ukrainian army's biggest hit against Moscow's arsenal since early 2022.

The blast from the strike was so strong that earthquake monitoring stations picked it up as if it were a minor earthquake, while NASA reported a series of heat sources spotted by its equipment from space.

The facility in Toropets is estimated to have stored around 30,000 tonnes of military munitions. The destruction of the ammunition that was stored there will most likely negatively affect the northern operational group of the Russian army.

But what is the Russian military storage facility in Toropets and how important is it?

Renovated in 2018, the facility in Toropets is estimated to have stored tonnes upon tonnes of military goods, including explosives, artillery shells and ballistic missiles.

The former Russian deputy defence minister Dmitry Bulgakov — who was arrested earlier this year on corruption charges — said after the renovations that the site met the "highest international standards" and could defend weapons from missiles and "even a small nuclear attack".

The storage site covered an area of over 5 square kilometres in size and a perimeter of more than 12 kilometres long. 

Which missiles were stored at the facility?

The town of Toropets is situated around 470 kilometers north of the Ukrainian border and the destruction of the ammunition that was stored there will most likely negatively affect the northern operational group of the Russian army, including the supply of troops in Kursk, Belgorod and Bryansk.

According to Ukrainian sources, the military site in Toropets reportedly housed fuel tanks, as well as missiles intended for Iskander missile systems, Tochka-U missile systems, guided aerial bombs and assorted artillery ammunition.

The head of Ukraine's Centre for Countering Disinformation, Andriy Kovalenko, said that in addition to its own ammunition, Russia had also started to store North Korean munitions in Toropets.

Maxar satellite service collected imagery clearly shows the extent of the damage from the Ukrainian drone attack causing a series of explosions, according to a photo shared by the Russia Team Lead at the Institute for the Study of War (ISW). 

The imagery shows large pillars of smoke covering much of the area, while a closer look at the ammunition storage area indicates that fires continue to burn in and near some bunkers, ISW's George Barros added.

Have the storage bunkers been destroyed?

Most of the ammunition is presumably stored underground, so the question is whether Ukraine used any drones that could have penetrated inside the bunkers.

A full damage assessment remains impossible due to the thick smoke above the site. However, the possible destruction of the bunkers might have also been the result of Moscow not respecting its own regulations by placing the bunkers too close together, for example.

While repeatedly calling on the West to lift the restrictions over the use of long-range missiles deep into Russian territory, Ukraine has been using its home-produced UAVs to strike as deep as 1,800 kilometres into Russia, as was the case in the city of Orsk.