Britain and France have signed an agreement to jointly develop long range missiles for future use by their navies and air forces.

British Minister for military purchases Harriett Baldwin and her visiting French counterpart Laurent Collet-Billon agreed in London on Tuesday to invest €50 million (£43 million) each to begin a three-year concept phase for the project.

Dubbed the Future Cruise/Anti-Ship Weapon program, arms manufacturer MBDA would explore options to replace and improve existing naval and air force weapons systems over the next 10 years, according to a statement by the UK ministry of defense.

The concept phase is focused on determining the designs of the future weapons and cutting the risks to a minimum before heading to the next stage in the cooperation, the statement added.

Beside costs, both sides also agreed to freely use one another’s “national technology expertise, trials and test facilities.”

“As demonstrated by having Europe’s largest defense budget, the UK is committed to European security and we will continue to collaborate on joint defense programs across the continent,” Baldwin said.

Collet-Billon also hailed the agreement, calling it “the backbone of our ‘one complex weapon’ initiative.”

Formed by a merger of French Aérospatiale-Matra Missiles, Italian Alenia Marconi Systems and British Matra BAe Dynamics, MBDA already produces Storm Shadow/ SCALP EG long-range cruise missiles for the British and French air forces.

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In late February, the two sides signed a £146 million deal to upgrade the £790,000 missile, which has a range of approximately 560 kilometers (300 nautical miles).

According to the British defense ministry, France is “the UK’s most important European Ally” and together, the two countries accounted for almost half of all military spending in Europe.

As London prepares to leave the European Union (EU) following last year’s July referendum, British officials have reassured their allies in Paris that nothing can undermine their military alliance.

“This is a day-to-day, intense partnership that has never been affected by whatever French or British-bashing was going on in either country in the last five years,” said Claire Chick, head of military affairs at the London-based Franco-British Council.