Ukraine has cracked the riddle of strange metal "whiskers" that appeared on Russian jet-powered drones striking Kyiv, and they don't appear to be some clever new sensor. They are a simple mechanical detonator, a metal tube, and a rod that, on impact, closes a circuit to set off the warhead, Serhii "Flash" Beskrestnov, presidential adviser, says, ending online guessing about the strange devices.

Photos of Russian drones with long metal prongs jutting from the nose had set off speculation about what they were for. The answer, Flash explains, is low-tech: when the prong hits something, the contact closes, and the charge goes off, with no sensors or electronics.

That simplicity sits against a more worrying trend: Russia is steadily upgrading what its drones carry, from the mix of warheads on the jet-powered Geran-4 and Geran-5 to a new charge designed to sever power pylons.

A contact closes the circuit

"It's all mechanically simple, no sensors or complex detectors," Flash says, commenting on the "whiskers".

It is the kind of crude, cheap fuze that suits a weapon meant to be built and spent in the thousands, where cost matters more than finesse.

Russia upgrades the warheads

Russia's jet drones, now built at roughly 3,000 a month, have become the dominant threat in its nightly campaign. The day when Flash published his "whiskers" post, Russia hit Kyiv with another round of drone strikes, hitting a school, a café, and warehouse buildings across the capital. The children inside the school were in its shelter. Fires broke out across two districts, and one person in the city was wounded.

On 28 September, Russia struck Kyiv's Academy of Sciences, which has a century-old history.

After Russia hits Kyiv’s Academy of Sciences with jet-powered drone, the Kremlin says Ukraine must “pay a price”

On the same day, Dmitry Peskov, Kremlin spokesperson, said Ukraine must "pay a price" for its actions in recent months and calls Russia's intensified strikes "part of this price."