What are the ‘kamikaze’ drones Russia is reportedly using?

A new wave of deadly Russian air attacks on Ukraine has killed more than 25 people and wounded more than 100, according to authorities in Kyiv, in the most extensive attacks since the early days of the war.

The current attacks, which began on October 10, have targeted at least 10 regions across the country and used Russian missiles as well as Iranian-made drones, according to Ukrainian authorities.

Swarms of explosive-laden, unmanned aircraft called “kamikaze” drones targeted Kyiv on Monday, killing at least four people and targeting energy facilities.

Among the victims was a young couple expecting a baby in three months, according to the mayor of Kyiv.

The Ukrainian Air Force said it destroyed at least 37 drones on Monday.

For their part, officials in Tehran deny supplying Russia with the weapons.

Here is what you need to know:

Why are they called ‘kamikaze’ drones?

Unlike drones that return to base once missiles are launched, “kamikaze” or “suicide” drones are destroyed in an attack.

Al Jazeera’s defence analyst Alex Gatopoulos says these munitions can hover above an area to identify a target before diving to destroy it. They are also called “loitering” munitions.

Like cruise missiles, they can hit targets hundreds of kilometres away, but cruise missiles are expensive, and Gatopoulos said “kamikaze” drones are a cheaper, yet precise, alternative.

Ukrainian President Volodymyr Zelenskyy said Russia had bought 2,400 “kamikaze” drones but its fleet is being depleted quickly.

Where do they come from?

Ukraine says Russia imported the drones from Iran, where they are known as Shahed-136, which could be translated as “witness of faith” but also as “martyr”.

Mykhailo Podolyak, an adviser to the Ukrainian president, accused Tehran of being responsible for the “murders of Ukrainians”. The Kremlin did not comment.

Iran, which has called NATO’s presence in Eastern Europe the root cause of the war, has denied supplying Russia with arms.

Gatopoulos said the drones are unlikely to be Russian-made because Moscow “has been behind in developing low-end tactical drones, especially armed ones”.

Samir Puri, an analyst at King’s College London, told Al Jazeera that some form of a sales agreement is likely to have taken place between Moscow and Tehran.

These drones were “bought off the shelf from Iran, moved to the war zone and being used, I think, very much as a weapon that will continue to confuse Ukrainian air defences by adding something else in the mix,” Puri said.

Will they change the course of the war in Ukraine?

“Kamikaze” drones cost significantly less than cruise missiles, but they still aren’t cheap.

One reportedly costs about $20,000, Puri said.

“That’s actually quite a lot when you think about the fact that they are, by definition, a one-use weapon.”

Their use in swarms presents a challenge to Ukrainian air defences, a Ukrainian air force spokesman told The Associated Press.

Western nations have promised to bolster Kyiv’s fight with systems that can shoot down drones, but much of that weaponry has yet to arrive and, in some cases, may be months away.

While the deployment of unmanned aircraft “will give the Ukrainians yet another weapons system to worry about”, it is unlikely to be a game changer, said Puri.

“In and of themselves, no one weapon system of this nature can change the outcome of the war,” he said.