French President Emmanuel Macron on Friday criticised Belgium's decision to buy US-made F-35 fighter jets instead of European planes, saying that "strategically it goes against European interests".
The Belgian government announced Thursday that it would replace a fleet of ageing F-16 jets with the F-35 made by Lockheed Martin, rejecting rival offers to buy Eurofighter Typhoons or Rafales from the French group Dassault.
"The decision was linked to a Belgian procedure and the country's political constraints, but strategically it goes against European interests," Macron told journalists during a visit to Bratislava.
"Europe won't be strong unless it is truly sovereign and knows how to protect itself," he said, citing a need to develop "a genuine European defence capacity".
"I will do everything possible to promote European offers in future contracts," Macron added.
Critics said the choice of Lockheed would leave Belgium dependent on maintenance and operational systems firmly in US control, while also assailing a blow to Europe's efforts to unify its defence capacities.
Belgium justified the decision by saying the F-35s offered better value for money while best allowing it to meet its NATO commitments.
Prime Minister Charles Michel said his country would be purchasing equipment from both US and European suppliers as it bolstered defence spending.
On Friday, the French defence ministry announced that Belgium had confirmed an order for 442 Griffon and Jaguar armoured vehicles for around 1.5 billion euros ($1.7 billion).
The deal had been expected, but the announcement appeared timed to allay tensions between the two NATO allies.
Last year the European Union launched its "permanent structured cooperation on defence", or PESCO, aimed at unifying defence strategies across the bloc and rationalising a fragmented approach to buying and developing military equipment.
The EU itself is planning to vastly expand its defence budget starting in 2021, allocating some 13 billion euros over seven years to research and develop new equipment -- up from less than 600 million euros in the current budget.
Most countries see no problem allowing non-EU firms to compete for contracts under the PESCO cooperation, but France is leading a handful which want to restrict their participation.
But Washington has warned that excluding US companies could undermine NATO at a time when tensions are running high with Russia and new threats such as cyber attacks are emerging.
On Friday the European aerospace consortium Airbus also said it took note of Belgium's decision not to choose the Eurofighter Typhoon with "sincere regret".
"It is a lost opportunity to strengthen European industrial cooperation in times when the EU is called upon to increase its joint defence efforts," the company said.
It added that in buying Typhoons, Belgium could have eventually joined the French-German Future Combat Air System, aimed at developing next-generation jets to start replacing current Eurofighter and Rafale jets starting in 2035.
Airbus is one of the partners in the Eurofighter consortium, which also includes companies from Britain, Germany, Italy and Spain.
Macron, speaking at the start of a two-day visit to Slovakia and the Czech Republic, also called on people to reject leaders who seek to "divide Europe".
"I will fight wherever they are trying to roll back justice, the ability of journalists to work freely, the role of universities, all which makes us European," he said.
Macron is hoping to counter a surge in support for populist parties and leaders in many European countries ahead of European Parliament elections next May.