It is a fear that Mr Trump and his aides seem to share privately. Boeing also shared this concern, with one industry insider saying it was “accurate” that concerns about the weaponry falling into enemy hands were a concern for top officials.

There were reportedly other fears, too.

According to the Atlantic, Raytheon and Lockheed Martin – the two other US defence companies behind the Patriots – were concerned that if granted a licence, Ukraine could improve the interceptors and produce them faster and at significantly lower costs.

Citing a Republican official on Capitol Hill, this was said to be another key reason for the White House denying Ukraine the licence.

“Their real worry is that the Ukrainians will find a way to improve the Patriot and then produce them at scale faster and for much less money than what the existing production lines in the US could do,” the source told the magazine.

A prime target for Moscow

There is also the issue of where Ukraine would physically assemble the missile. Building it within the country would make it a prime target for Russian strikes.

Two sources familiar with the discussions said as a solution, new interceptors would probably be manufactured in Germany or another European country.

It is an idea understood to be favoured by Elbridge Colby, the United States undersecretary of war for policy.

But experts and insiders say moving production outside Ukraine would take time and further complicate licencing.

Germany, for example, has not finished production at its new Patriot missile factory.

Fabian Hoffmann, a missile expert at the University of Oslo, told The Telegraph: “Both concerns are justified. Agreeing to license production always implies intellectual property risks for the manufacturer that can’t be taken lightly.”

He added: “Patriot facilities would also be a prime target, but everyone is aware of that. So if production were to be relocated, it would have to be moved underground and dispersed. That’s why licensed production would take a long time to establish and be difficult to set up efficiently.”