Nato allies' equivalent drones can be twice as expensive as they try to shun Chinese components.

However, there are still weapons that Ukraine needs and struggles to produce on its own. From fast fighter jets to the most urgent example, interceptors to take down Russian ballistic missiles

The most effective weapon to do that, by far, is the US-made Patriot interceptor. Ukraine has all but run out of them and Russian ballistic missiles now make it through Ukrainian air defences with ease.

America's war in Iran has meant they're in even shorter supply.

They're also expensive – at around £3m a missile – and production rates have been slow. The US is planning to double production rates from around 600 Patriot missiles per annum to 2,000, but that will take several years.

President Donald Trump signalled last month that he would be willing to share Patriot technology with Ukraine, but has since rowed back.

Even if he had given approval, it would have taken a while for Ukraine to make Patriots themselves - some estimate at least a year. Ukraine would also be relying on the same sophisticated components that are in high demand across the globe.

Ukraine has embarked on a programme to develop its own interceptor missiles with European support – known as Project Freya.

But there are huge technological challenges in building a high-speed missile to take down another missile travelling at thousands of miles per hour. It is expensive and often time consuming.

Ukraine's military and its weapons manufacturers have shown themselves to be fast learners.

One of its own companies, Fire Point, is developing its own ballistic missiles which it hopes will be ready to fire in anger next year.

But Russia has already ramped up its own ballistic missile production, to around 100 a month.

Developing sophisticated weapons is expensive and cannot be done quickly. Ukraine is short of both time and money.

So, the move to hand missile blueprints to Ukraine will be welcome, but it is not an immediate fix for Ukraine's most pressing problems, and it wwill not dramatically alter Kyiv's ability to strike Russia in new ways.