Flying several kilometers in the air and close to the speed of a commercial plane, Moscow's new long-range jet-powered drones are causing havoc for Kyiv's stretched air defenses.
Moscow has been launching waves of the attack drones at the Ukrainian capital in recent weeks, paralyzing the city with near constant air alerts.
President Volodymyr Zelensky on Sunday slammed the "horror that's been happening in the sky these past few days" as a new tactic by Russian leader Vladimir Putin, and vowed a response.
The new drones pose a challenge to Ukraine's relatively effective and low-cost anti-drone defense shield, built hastily after Russia's 2022 invasion.
Ukraine has quickly become a world leader in drone defense and has struck deals with several Western and Middle Eastern countries to share technology.
But its vaunted network of drone interceptors -- which had been shooting down the vast majority of more conventional drones, built with internal combustion engines and propellers -- has had a harder task against the new jet-powered devices.
Experts say they are fitted with Chinese-made aircraft-style mini jet engines, and can fly five kilometers in the air at a speed of 400-600 kilometers (250-370 miles) per hour -- up to three times the rate of the previous versions, which were based on Iran's Shahed drones.
The latest model can carry up to 90 kilograms of explosives, nearly double the payload of earlier versions, and is much bulkier -- six meters long with a 5.5-meter wingspan.
That altitude and speed puts them out of range for Ukraine's current fleet of interceptors and "wipe out the progress we had made in the fight", Ukrainian military expert Sergiy Zgurets told AFP.
In terms of air defense, analysts say the new drones more closely resemble a cruise missile than a conventional drone.
It is estimated that Russia fired 2,800 of the jet-powered drones in August, up from 1,500 in July and just a few hundred in June.
A Ukrainian air force spokesman said around 60 percent of them are destroyed, compared to more than 90 percent of the slower-moving lower-flying drones.
- City at standstill -
The new attacks come with Kyiv already strained by a sharp increase in Russian ballistic missile strikes, which have killed dozens since the start of the summer.
On Friday, a jet-powered drone struck the headquarters of Ukraine's security services in the historic center of Kyiv, a highly symbolic hit carried out in broad daylight.
Ukraine accused Russia of using the strike to disrupt the weekend visit of US envoys Steve Witkoff and Jared Kushner to both Moscow and Kyiv to try to revive stalled peace talks.
The wave of attacks has brought Kyiv to a near-standstill at times, with up to a dozen air alerts ringing out every day.
During alerts, many businesses and institutions close and the metro service is restricted, causing gridlock on the roads and people to gather outside on the street.
Many schools, which returned from summer break last week, have announced a switch to remote learning.
The situation has disrupted social and economic life to such an extent that the authorities announced a rare relaxation of security protocols to allow the city of some three million people to keep functioning.
- Six-month wait -
Kyiv officials have been criticized for failing to anticipate the threat.
Analysts say Russia started producing jet-powered drones 18 months ago, and can now churn out some 3,000 a month.
Moscow "has a window of opportunity with these jet drones", said Ukrainian blogger Nikolaevsky Vaniok, who is close to the country's air defense community and followed by more than 2.6 million on Telegram.
Faced with the threat, Zelensky convened his military cabinet last week to speed up the production of faster interceptor drones.
Prototypes exist and work is under way "to bring this new weapon up to the required level of efficiency", he said.
One major Ukrainian arms company that makes interceptors for conventional drones told AFP they were "actively working on a solution".
Zgurets, the head of the Defense Express analysis center, said Ukraine needed a more complex response than just better interceptors.
A fuller response would combine aviation, surface-to-air systems, electronic warfare and more strikes against launch and production sites inside Russia, he said.
"The Russians have gained an edge in this technological cycle," he said, warning it could take "up to six months" for Ukraine to develop effective countermeasures.
