Ukrainians were beginning to think they had won their “winter war” after riding out Russia’s repeated bombardment of their country’s power and heating system. A devastating missile strike early on Thursday — in which Moscow used several of its formidable hypersonic Kinzhal missiles — sent a brutal reminder that the threat is far from over.

“It is a mistake to think that they are done with their attacks on the population, [done] with their missile strike campaign on electricity infrastructure,” Oleksiy Danilov, Ukraine’s national security chief, told the Financial Times.

“This is not a war between soldiers and soldiers. This is a war aimed at destroying critical infrastructure facilities . . . the provision of light, water and heating.”

Russia fired 81 missiles, including six Kh-47 Kinzhals at targets across Ukraine. It was the first mass strike away from the front lines in more than three weeks. Three thermal power stations were hit and the Zaporizhzhia nuclear plant temporarily lost its electricity supply needed to cool its reactors.

Since late January, Ukraine’s electricity supplies had begun to stabilise as the power grid was made more resilient and improved air defences shot down the bulk of Russian missiles and attack drones.

But on Thursday, only 38 of the 81 missiles were intercepted, while another eight were knocked off target by countermeasures. That is a notably lower interception rate than the 80 per cent notched up by Ukraine’s air defence forces earlier this year.

The missiles destroyed were mostly subsonic cruise missiles and slow-flying attack drones. None of the 25 high-speed or ballistic missiles of various types, including the Kinzhals, were shot down. Ukraine’s air force said it did not have the capability to do so.

Moscow is believed to have used its air-launched Kinzhal missiles against Ukraine before, but never in such a salvo.

It was unusual, said Justin Bronk, senior research fellow at the Royal United Services Institute in London, because the Kinzhal is a scarce and highly sophisticated ballistic missile designed to overcome the most advanced air defence systems. It can fly at 10 times the speed of sound.

“It is one of a handful of specialist systems which, in a clash with Nato for example, Russia would have to be careful about how it chose to use,” said Bronk, adding that Russia probably only had “tens” left in its armoury.

A Ukrainian military intelligence official said Russia started its invasion in February last year with about 50 Kinzhals in stock and had fired about 15 at Ukraine before Thursday’s strikes.

The attack does not amount to a change in Russian tactics, said Yuriy Ignat, Ukraine’s Air Force spokesperson. Over the past year, Moscow’s forces have fired several hundred Iskander ballistic missiles as well as other super high-speed missiles, such as the powerful Kh-22, which has a 950kg warhead, and the S-300, which is normally used as an air defence interceptor.

But the use of so many precious Kinzhal missiles is baffling. There were three possible explanations, said Bronk. First, Russia may have been trying to overcome air defences at a particular site in Ukraine, although he pointed out that the Iskander M ballistic missile, used in much larger quantities, had already been proven hard to stop.

The second was that stocks of other ballistic missiles were running very low. The Ukrainian military intelligence official claimed Moscow had only about 90 Iskander M, 45 Iskander K and 36 Kh-22 missiles left. Ukrainian officials believe western sanctions are heavily constraining Russia’s missile production capacity, although Bronk said Moscow may still be able to make six Iskander M missiles a month.

“What they fired overnight is equivalent to what they can produce in one month to replenish stocks,” said the military intelligence official.

The third reason, Bronk said, was Russia’s “consistently odd allocation of weapons to target sets”, using precious sophisticated armaments to strike Ukrainian positions or infrastructure when a lesser weapon would do. This could partly be explained by Moscow’s centralised decision-making, far away from the front lines.

Ukrainian officials said the strikes underscored the need for more sophisticated, longer-range air defence systems and the speedier deployment of those already promised by its western allies.

Ukraine’s air defences have improved markedly over the past year, with new western equipment and better techniques, but it still lacks surface-to-air capabilities to intercept fast-moving ballistic missiles.

A senior Ukrainian official told the Financial Times that his country is hoping to soon receive its first batches of Patriot air defence systems promised by the US and European countries.

The Patriot is the most advanced medium-range air defence system the west can offer — but it has not been tested against Kinzhals. A similar system, the Samp-T, promised by France and Italy, is also yet to arrive.

“We need weapons, weapons and more weapons,” Danilov said. “Russia will continue to increase the degree of aggression if the world remains silent.”

The originally reported information in this story that Ukraine had already received a first Patriot system was not accurate. The story has been updated accordingly.