HALIFAX, Canada — A top uniformed NATO official warned Friday the European Union army concept endorsed by French President Emmanuel Macron and German Chancellor Angela Merkel would be “duplicative” and “unwise.”

In an interview at the Halifax International Security Forum, U.K. Air Marshal Stuart Peach, chairman of the NATO Military Committee, pointed to NATO’s strength as a single set of forces, with a unique command-and-control network and planning process.

“It’s not rhetoric-based. It’s real planning based on real data,” Peach said. “And therefore, why would you wish to duplicate or replicate the strengths of an existing strong alliance?”

The comments came after Merkel on Tuesday floated the idea of a “real, true European army” to complement NATO. Her remarks, made during a session of the European Parliament, virtually echoed Macron’s call a week earlier in an interview with Europe 1.

U.S. President Donald Trump called Macron’s comments “very insulting” in a spate of Twitter posts as the two held a meeting last week in Paris.

Trump has tested the strained bonds with some of America’s closest allies by pressuring fellow NATO members to rely less on the U.S. and dedicate a greater percentage of their gross domestic products to defense.

On Tuesday, NATO Secretary General Jens Stoltenberg alluded to the proposal of a European force at a NATO conference in Berlin, saying he welcomed “increased EU efforts on defense because I think that can actually help to strengthen NATO.”

European allied militaries can act without the U.S. so long as they use NATO command structures, Stoltenberg said.

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“It will be not a wise decision by all those nations who are members of both NATO and the European Union to start to have two sets of command structures, or duplicate what NATO is doing,” Stoltenberg said.

On Friday, Peach referred to Stoltenberg’s remarks, saying: “Of course, as chairman of the Military Committee, I agree with [Stoltenberg]. It’s unwise to duplicate.”

Peach emphasized that NATO has a “single set of forces, and in our processes, those forces are trained and assured and certified by NATO.”

At the conference, Peach had a broader message, that the alliance’s 29 members remain committed and that NATO is adapting with the times.

“Throughout the history of the alliance there have been inevitable tussles about how to go forward,” Peach said. “But throughout, as a military alliance, we have adapted our command-and-control structure, responded to new challenges, embraced new members, and continued to adapt to new types of warfare and new threats.”

Separately, Finland and Norway intend to launch diplomatic discussions with Moscow over suspected GPS signal-jamming by Russia’s military, which overlapped with NATO’s Trident Juncture exercises, the largest maneuvers in the High North since the end of the Cold War.

Peach on Friday would not confirm the interference took place, but called the principle of freedom of navigation “very, very important, both to NATO and the international community.”

“Freedom of navigation is not just freedom of navigation at sea, so we need to analyze claims with data. And anything that interrupts freedom of navigation is important to be reported," he said.