"When it comes to military equipment... we need to build more, we need to expand our industrial base," Supreme Allied Commander Europe Cavoli said at D-Day 80th anniversary commemorations in Normandy.

But he added that NATO "is ready to do collective territorial defence", pointing to a vast exercise dubbed Steadfast Defender 24, which involved 90,000 allied troops across multiple European countries from January to May.

"We've shifted our focus entirely over the last couple of years, we used to do out-of-area operations, now we're focused on defending the territory of the alliance," Cavoli said.

Russia's invasion of Ukraine and Kyiv's Western-backed defence have shown the vast appetite of modern conflicts for ammunition and other equipment.

It has however taken time for defence manufacturers to ramp up output of items from artillery shells to vehicles and drones.

"We need to generate hardware more quickly. I think all the nations in the alliance realise that and are working on it," Cavoli said.

The general added that NATO is "going to take a very deliberate effort to study everything about the conflict so that we can develop from it".

He cited "innovative uses of hardware", such as the low-cost drones used by both Russia and Ukraine for reconnaissance and attack.

NATO troops would also be learning from "techniques and tactics" used on Ukrainian battlefields at a new "lessons learned" centre to be set up in Poland, Cavoli added.