The heads of the EU and NATO on Thursday discussed efforts to bolster Europe’s arms production, as US President Donald Trump throws doubt on Washington’s commitment to the transatlantic alliance.

“We need to invest more, to produce more and to do both faster,” European Commission president Ursula von der Leyen posted online after meeting NATO chief Mark Rutte.

European nations are scrambling to bolster their militaries in the face of Russia’s war on Ukraine and pressure from Trump.

Fears over Washington’s role in NATO have been heightened as the mercurial US leader has threatened he could leave the alliance in anger over the European response to his war in Iran.

NATO allies last year pledged to ramp up core defence spending to 3.5 per cent of GDP in a bid to assuage Trump’s criticism that Europe was not spending enough on defence.

But there are ongoing complaints that Europe’s defence industry is failing to keep pace and is not able to meet the new, higher demands despite a raft of initiatives from the EU.

NATO officials say that the issue of industrial production is set to be one of the central topics for the alliance’s upcoming summit in Ankara.

Rutte — who held talks with Trump in Washington last week – posted online that a “stronger Europe means a stronger NATO”.

He wrote that he had discussed with von der Leyen “how to further strengthen our essential NATO-EU cooperation, including ramping up defence industrial production, continuing vital support to Ukraine, and protecting critical infrastructure.”

The United States has said it wants to see European allies take over the conventional defence of their continent, so that Washington can focus more on other threats such as China.

European countries meanwhile are realistic that decades of relying on America to keep Europe safe are over and that they increasingly will have to take their security into their own hands.

The EU — which long shied away from defence issues — has massively ratcheted up its efforts to bolster industry in recent years, and some countries are asking if it can play a bigger role.

NATO officials insist that the bloc should focus on its core strengths such as marshalling funding and not stray into the alliance’s traditional field of military planning.