Donald Trump has made Nato stronger by forcing European member states to spend more on defence, Grant Shapps said on Thursday, amid growing fears over America’s commitment to the alliance.

The Defence Secretary said the former president’s concerns over defence spending had been addressed because “countries are stepping up and doing the right thing now”.

Jens Stoltenberg, the Nato secretary general, warned that European Union investment would not be able to replace the United States’ contribution to the Western military alliance.

A suggestion by Mr Trump that he would withdraw protection from Nato allies who failed to spend two per cent of gross domestic product on defence dominated a two-day meeting of the alliance in Brussels this week.

As defence ministers met in the Belgian capital, Mr Trump doubled down on his threat.

‘I’m not going to protect you’

Speaking at a rally in South Carolina late on Wednesday, he said: “I’ve been saying, ‘Look, if they’re not going to pay, we’re not going to protect, OK?’

“One of the heads of the countries said, ‘Does that mean that if we don’t pay the bills, that you’re not going to protect us?’ That’s exactly what it means. I’m not going to protect you,” he added.

In response, 18 of Nato’s 31 member states announced plans to hit the target, which was set a decade ago.

Speaking to reporters on the sidelines of the gathering, Mr Shapps brushed off fears over Washington’s future role in the US-led defence organisation.

“The world has had a Trump presidency before,” he said. “Nato, as I point out, is not just still here, it’s stronger, with more members and more money being spent on defence.

“Nato is by nature a transatlantic organisation. It is very important that others step up to the plate,” he added in a challenge to those failing to reach the spending goal.

Faced with the prospect of a Trump presidency and a mounting threat posed by Russia, European governments have promised to overhaul their militaries and ramp up weapons production in joint schemes.

EU figures have even discussed the creation of a European nuclear umbrella amid fears over a lack of US backing for the continent.

Some senior figures in Germany, including the country’s finance minister, took Mr Trump’s comments as a sign that the EU may need its own nuclear deterrent against Russia should he be re-elected.

Mr Stoltenberg said: “But that’s not an alternative to Nato. That is actually a way to strengthen Nato. And we should not pursue any path that indicates that we are trying to divide Europe from North America.”

The UK and Latvia launched an international drone coalition in support of Ukraine, which Mr Shapps said would allow British developers to test their creations on the battlefield.

The scheme is part of Britain’s pledge of £200 million towards Ukraine’s new unmanned force.

“Obviously, what we want to do is benefit Ukraine but also benefit British research and development and businesses in the process,” Mr Shapps said.

‘Drones likely to be part of war machines’

The scheme would see both Ukrainian and British-designed drones provided to Kyiv’s forces.

“But if you think about all future capability, then drones are likely to be part of our war fighting machines as well,” he added. “So there’s a clear benefit to being involved, not least to Ukraine, but also for us tomorrow.”

It will come as a welcome boost to Ukrainian forces who are increasingly being forced to ration ammunition on the front lines, according to a Western intelligence assessment.

Shell hunger has become prominent in areas of heavy fighting, such as the Donetsk region town of Avdiivka, while US military aid remains blocked by a political dispute in Congress.

A Nato official said Ukrainian commanders were having to make “very difficult, really tough decisions” on operational  manoeuvres.

The source said: “Some units are marshalling ammunition quite closely. They are deciding how many munitions to use on a given date. There is some sort of rationing going on. They certainly know they have to keep some back for other operations. I think it is clear that they are worried about running out.

“It is causing tough decisions for commanders all along the front. We see that Russian understanding of the pressure that is mounting on Ukrainian munitions in decisions to strike,” they added.