In the midst of Brexit negotiations, British Prime Minister Theresa May lays out her reasoning for a security relationship between the U.K. and the European Union at the Munich Security Conference. (Jeff Martin/Staff)

MUNICH — The United Kingdom’s prime minister sent a subtle message to the European Union that going it alone in defense development efforts without full cooperation with the U.K. would be a step backward in regional security.

Theresa May focused much of her speech at the Munich Security Conference on reassurances that an exit from the EU by the U.K. does not translate to an abandonment of collective European security. But in terms of defense research and development, May was pointed about the U.K.’s contributions.

“The U.K. spends around 40 percent of Europe’s total [investment] in defense research and development, and this provides a sizeable stimulus to improve Europe’s competitiveness and capability, and this is to the benefit of us all,” May said. “An open and inclusive approach to European capability development, that fully enables the British defense industry to participate, is in our strategic security interests.”

The remarks come amid much discussion and some skepticism about the recently formed EU joint defense agreement to ensure European members are not distracted from their NATO commitments. The Permanent Structured Cooperation on Security and Defence, or PESCO, goes hand-in-hand with the European Defence Fund, first announced in 2016, which could generate a total investment in defense research and capability development of €5.5 billion per year after 2020 for member states.

Some EU members — notably France, which has close bilateral defense ties with the U.K. — have advocated for greater integrated European defense, with Britain playing a key role. But how the U.K. and U.K. companies could participate in the fund is unclear once Britain exits the EU.

“The U.K. wants to agree on a future relationship with the European Defense Fund, and the European Defense Agency, so that jointly we can research and develop the best future capability that Europe can muster,” said May, pointing to the Eurofighter Typhoon — a joint effort with the U.K., Germany, Italy and Spain — as an example of the power of defense partnership.

She also pointed to the NotPetya cyberattack perpetuated by Russia against Europe as an example of why development cooperation in network security is so critical. And in the space domain, May noted that “the U.K. hosts much of Europe’s cutting edge capabilities on space,” with a leading role on the Galileo program as one example.

“The key for this is to continue as part of our new partnership, but as is the case more widely, we need to get the right agreements concluded, which will allow the U.K. and its businesses to take part on a fair and open basis.”