European countries have been told they will need to build drone armies and should start preparing now. The warning was issued by the EU’s Defence commissioner, and comes as military intelligence suggests a Russian attack on a NATO country could take place within the next five years.

Drones have helped Ukraine’s army repel attacks from its much bigger and better-equipped opponent, as well as transform modern warfare. Cheap to produce, they are estimated to be responsible now for 80% of Russian frontline losses.

Both Ukraine and Russia have ramped up production of their UAVS, churning out millions of the lethal weapons per year.

Kyiv is expected to produce some four million this year alone, while Russia has even greater capacity.

Andrius Kubilius said Europe must rise to the challenge and prepare its own armies of drones to defend itself from possible further Russian aggression.

“Russia can have around five million drones, so we need to have capacities bigger than those in order to prevail,” he told Sky News.

The commissioner is from Lithuania and estimates his country would require around three million drones a year to protect its 559-mile border it shares with both Russia and Belarus.

Drone technologies are changing all the time in a fast-moving environment, as new innovations are introduced.

As a result, Mr Kubilius believes it makes more sense for Europe to build up teams of pilots, engineers and manufacturers ready to scale up production when the time comes, rather than stockpile drones now.

The message appears to be getting through to NATO leaders, who met on Wednesday in The Hague for a “historic summit” where members agreed to ramp up defence spending to 5% of GDP by 2035.

NATO boss Mark Rutte said he wanted more investment in drone technology as well as boosting air defences fivefold.

“We see Russia’s deadly terror from the skies over Ukraine every day, and we must be able to defend ourselves from such attacks,” he told an audience at the summit.

The UK along with Germany and Denmark have already announced deals with Ukraine to produce drones.

Britain is also committed to producing more UAVs following the government’s Strategic Defence Review.