What do we know about drone attacks in Russia?

Russia has accused Ukraine of trying to kill President Vladimir Putin in a drone attack on his residence in the Kremlin in Moscow.

Two drones were brought down by Russian air defences, according to Kremlin officials who said Mr Putin was not there at the time.

Ukraine has denied this, claiming that Russia staged the attack.

In recent months, there have been a number of suspected drone attacks inside Russia and Russian-occupied territory in Ukraine.

Last month, a drone came down in the town of Kireyevsk, about 400km (249 miles) from the Ukraine border, injuring at least three people in an explosion after it was brought down, Russian state media said.

In February, a drone crashed in the village of Gubastovo, about 100 km (62 miles) from Moscow, in what the local governor said was an attempt to target civilian infrastructure.

A picture of the wreckage appeared to be consistent with a UJ-22 - a type of drone manufactured by Ukraine.

It has a range of 800km (497 miles) in autonomous flight. Its range under directly-controlled flight is much shorter.

In December last year, a drone attack hit an airbase 600km (372 miles) north-east of the Ukrainian border, according to the Russian military.

None of these attacks have been officially claimed by Ukraine.

However, Kyiv's military has said that undermining Russia's logistics forms part of preparations for its long-expected counter-offensive.

Since the start of 2023, the BBC - by analysing Russian media reports - has tracked over 20 suspected drone attacks inside Russia and Russian-controlled territory in Ukraine.

These have mostly been in the Bryansk and Belgorod regions in Russia, as well as in Russian-annexed Crimea - in particular, its capital Sevastopol.

Among the targets were oil facilities, airfields and rail lines.

Drones have been deployed by both sides in the conflict so far, with many used for surveillance and targeting.

In terms of range, experts say drones launched from Ukraine could reach Russian territory, and as far as Moscow, which is about 450km (280 miles) from the border.

"Although Ukraine has not confirmed that its armed forces carried out the attacks, I think that the pre-emptive raids we have seen last year prove that Ukraine has the capability to launch long range attacks of that kind from within Ukrainian territory," says aviation expert David Cenciotti.

Drone specialist Steve Wright also said it was possible that a drone could hit the Kremlin having been launched from within Ukraine.

But he added: "My guess is that the drone was launched from far closer in than that, as this would avoid it having to run the gauntlet of much of Moscow's defences."

Ukraine's Minister for Digital Transformation Mykhailo Fedorov recently boasted of a Ukrainian drone called the R18 that "can fly from Kyiv to Moscow and back".

But he denied that he was calling for drone strikes on Moscow.

Mr Cenciotti says: "Ukraine has made extensive use of several drones, with the Bayraktar TB2 drone emerging as the real star of the air war for Ukraine, inflicting heavy losses on Russian forces, some of those caught on tape and circulated online."

Turkey has sold Bayraktar TB2 armed drones to Ukraine in recent months, while the Turkish manufacturer of the drones has donated some to crowd-funding operations in support of Ukraine.

Ukraine says it is rapidly increasing its production of drones as demand grows on the front line.

Additional reporting by Joshua Cheetham, Thomas Spencer, Shayan Sardarizadeh and Paul Brown