They're slow, loud and 'bargain-basement.' So why is Russia using kamikaze drones against Ukraine?

Ukraine's capital city of Kyiv was struck on Monday by a flurry of suicide drones that attacked residential areas, causing widespread damage to buildings, setting them afire while killing at least four people. 

These weapons, also known as kamikaze drones, are not new to the battlefield, having being used to attack military and infrastructure targets in southern Ukraine since September, the Washington Post reported.

But their use on civilian targets raises questions of whether this is a new strategy by Moscow or a sign of a problem with its military campaign. 

CBC Explains what are these drones, their advantages, disadvantages and why Russia is using them against Ukraine.

They're known as "loitering munitions," but also have been labelled suicide or kamikaze drones. They are used once, destroying themselves when they hit their target, much like the Japanese pilots in World War II who flew suicide missions into U.S. warships and aircraft.

"They are strapped with explosives, payloads, various things like that," said Nicholas Carl, the Middle East portfolio manager of the American Enterprise Institute's Critical Threats Project. "So the Russians can target them at various locations." 

But unlike missiles that go straight from launch to their target, drones can hover — waiting hours before they strike.

U.S. and Ukrainian officials say these specific drones are Shahed 136s, manufactured by Iran. Ukrainian President Volodymyr Zelenskyy has said that, according to their intelligence, Russia has ordered 2,400 Shaheds from Iran, though Iran denies having supplied any such drones to Russia.

They are relatively small; about 3.5 metres long and two metres wide, weighing around 200 kilograms and powered by a 50-horsepower engine with a top speed of 185 km/h, according to the Ukrainian online publication Defence Express. They can be launched from the back of a truck. 

These particular drones are like "crude and bargain-basement" cruise missiles, wrote Douglas Barrie, a senior fellow for military aerospace with the International Institute for Strategic Studies. 

They're not very accurate and are slower than, for example, an actual cruise missile. So they can be shot down more easily and are vulnerable to jamming, says Christopher Tuck, an expert in conflict and security at King's College London.

"They are pretty low-end, they're slow and they're pretty noisy," Tuck said. "They really aren't very sophisticated."

The loud buzzing made by the motor has earned them another nickname: "moped" missiles.

The Shahed 136s also don't carry much explosives — the payload for one is about equal to three mortar shells, Carl says; they have "limited utility" against Ukrainian forces.