What is remarkable is that just 15 months before Ukraine's successful attack on Moscow and at the start of the all-out war in February 2022, Ukraine's total drone force consisted of only two reconnaissance drones - equipped with cameras not warheads.

The military, working with Ukrainian manufacturing companies, quickly realised, however, that so-called "kamikaze drones" would be valuable weapons in the war against President Vladimir Putin's Russia.

"The whole nature of warfare has changed drastically in just three years and in some areas we have been able to gain an advantage over the enemy," Borets told me.

"Some of our capabilities, including the use of aerial and sea drones, have surprised Russia, particularly because of the long range of our strikes, up to 1,000 miles. Our limitations in the early days of the war were that we did not have enough drones or else we would have done considerably more damage to the enemy's war machine."

Of course, Russia too is making improvements to its drone technology. Putin's forces staged blistering strikes across Ukraine last week just hours after Kyiv signalled it was ready for a ceasefire following talks with the United States.

However, Borets told me: "Russia is catching up but, in general terms, it is three to four months behind us. The production cycle changes and gets upgraded every six months - whatever was being used six months ago needs to be improved and that triggers constant innovation."

As we criss-crossed the snow-covered roads for nearly an hour in an anonymous white VW van, I had no idea where we were heading. All I knew - as the daytime temperatures dipped to -4 Centigrade - was that, because of my unstinting support for Ukraine's war effort, I was being taken to a highly-secretive destination to see the cutting-edge work of the world's leading drone manufacturer.

We arrived at a grey, nondescript building and, just minutes later, I was entering a vast, pristine showroom, in which five hi-tech drones were displayed. I felt like James Bond being shown his latest deadly gadgets by Q, the head of the British Secret Service research and development division.

Yet whereas that was fiction, the weaponry in front of me was very real, as was my host for the afternoon, a shadowy figure with the call-sign "Borets", the chief of the "9th", a special forces department within Ukraine's Defence Intelligence agency.

Borets, quietly spoken, calm and authoritative, and "Serhii", the astute chairman of Ukraine's leading drone-manufacturing company, then proceeded to give me a guided tour of the aerial weapons that have been able to strike deep - at times 1,000 miles - into Russian territory over the past three years of the all-out war that began with the Russian invasion of February 2022. Only last week, a reported 337 drones attacked Moscow - the biggest such strike yet of the brutal conflict.

And if US-UK-brokered peace talks currently underway fail, it's likely more such attacks using these state-of-the-art unmanned aerial vehicles will follow.

First on show was the Beaver UJ-26 drone with a 30-kilo warhead, a range of nearly 600 miles and a maximum speed of 194mph. It was this model of drone that was first used to strike the Russian capital of Moscow less than two years ago. The attack caused alarm in the Russian capital - which its military leaders had wrongly considered out of the range of Ukraine's drones - and a massive boost to the morale of the Ukrainian military and civilians alike.

Similarly, Borets revealed it was the Beaver drone, used in conjunction with more conventional missiles, that had caused panic among Russia's leaders when it attacked the famous Kerch bridge, a 12-mile long roadway connecting Russian with illegally-occupied Crimea. Borets told me: "We are proud whenever we have a successful strike that destroys or damages its target. Every time we learn from what has happened and move on to our next assignment."

The early drone strikes deep into Russian soil had given him the greatest satisfaction. Apart from that first attack on Moscow, he singled out the successful attack on Shaykovka air base in August 2022 which destroyed several enemy aircraft.

More recently, there was a successful attack on a Russian radiolocation station that had been used to identify Ukrainian missile launchers, thereby preserving many lives.

Within recent months too, aerial drones had been used in a strike badly damaging three Cruise-missile carrying enemy ships in the Caspian Sea and attacking Primorsko-Akhtarsk airfield in Russia, which was being used to launch Iranian-made Shaheed drones against Ukraine.

Long-range aerial drones are used regularly by the "9th" unit to attack enemy targets ranging from airfields to ships and from oil refineries to armament factories.

I asked Borets if they had ever been used to assassinate key enemy figures.

He paused for a long time before replying "tak" - Ukrainian for "yes" - but declined to elaborate further. Targets are identified from a range of sources, including agents operating inside Russia. Beaver drones, which have a wingspan of more than five metres and cost around £80,000 each, have proved hard to shoot down or to "jam" because they are engine-powered, low-flying and fast-moving. Like all aerial drones, they are unmanned which means even if they are intercepted, no lives are lost.

I asked Borets, who is bearded and 36 years old, if he considered, after three years of war, that Ukraine is now the world leader in drone technology. Once again, he thought long and hard before replying: "Tak, tak."

I was also shown one of the earliest aerial drones, a UJ-24 Baklan model, named after a native sea bird, that two years ago was considered state-of-the-art but has now been overtaken by improvements in technology.

The "9th's" long-range attack capability consists of aerial and sea drones while its shorter-range capability consists of weapons such as land robots. Whenever possible, these weapons are used in conjunction with each other to maximise an attack.

I was also taken to a second secret location by Borets where I met, for the second time in three months, another mysterious figure whose face was again covered by a camouflage-patterned ski-mask. The man, who identified himself only as "Thirteenth", had been my host when I wrote an exclusive report for the Daily Express, this time on the success of Ukrainian sea drones.

He refuses to reveal his identity because he is from the Group 13 unit, operating under the command of the "9th" department, that was responsible for using sea drones to neutralise Russia's Black Sea fleet.

When I met him in November last year, Thirteenth told me that his unit had sunk nine Russian ships and large boats, and hit and damaged six more. It meant, along with strikes using more conventional weapons, at least a third of the enemy's fleet has been destroyed or disabled.

On that occasion, he has given me, as a souvenir, a small model of the Magura V5 which costs around £200,000 per weapon. This time Thirteenth wanted to show me the life-size Magura V5.

Speaking in his native Ukrainian through an interpreter, Borets told me his department had equipped sea drones with R73 short-range missiles which, as recently as December last year, had been used to destroy two Russian Mi-8 helicopters over the Black Sea and to damage another Ka-26 military helicopter.

"This breakthrough has meant enemy helicopters are no longer flying over the Black Sea and it is also helping to sustain the 'grain corridor' [by which Ukraine exports vast quantities of wheat and other crops from southern ports]."

Borets added matter-of-factly: "Our aim now is to equip the sea drones with missiles or rockets that are capable of shooting down Russian fighter jets."

Once again, I did not leave my visit empty-handed.

My new gifts were a model of both the Beaver aerial drone and the very latest Magura sea drone, as well as a copy of an artist's painting depicting the first successful drone strike on Moscow.

These are challenging times for the Ukraine and dangerous times for the wider world. However, until the war stops, Russia will always know that, while the 9th department exists, no area of its home soil is entirely safe from attack.

Lord Ashcroft KCMG PC is an international businessman, philanthropist, author and pollster. For more information on his work, visit lordashcroft.com. Follow him on X/Facebook @LordAshcroft