(Bloomberg) -- The EU hit back over U.S. accusations that military cooperation between European countries might weaken NATO and prevent American companies from participating in defense projects.

The European Union’s foreign policy team said that the “EU remains fully committed to working with the U.S. as a core partner in security and defense” that the bloc’s initiatives strengthen NATO rather than undermine it, according to a letter dated May 16.

The Financial Times reported on May 14 that U.S. Undersecretary of Defense Ellen Lord and Under Secretary of State Andrea Thompson sent a letter to the EU setting out why they were “deeply concerned” that the EU’s defense plans “produce duplication, non-interoperable military systems, diversion of scarce defense resources and unnecessary competition between NATO and the EU.”

Their worries focus on two EU initiatives, the 13 billion euro European Defense Fund and the Permanent Structured Cooperation, or PESCO, which includes projects such as the development of common technology for European military radios and the sharing of cyber attack intelligence.

“Addressing NATO requirements and avoiding any unnecessary duplication with ongoing efforts are among the key criteria for the selection of PESCO projects,” the EU says in its letter. “It is clear that PESCO and the EDF are designed to support capabilities that are coherent, complementary and interoperable with NATO.”

--With assistance from Jonathan Stearns.

To contact the reporter on this story: Ian Wishart in Brussels at iwishart@bloomberg.net

To contact the editors responsible for this story: Ben Sills at bsills@bloomberg.net, Nikos Chrysoloras

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