BRUSSELS — U.S. Deputy Secretary of State Christopher Landau on Wednesday slammed European NATO allies for prioritizing their own defense industry over American arms suppliers, according to three NATO diplomats.

The intervention came during Wednesday’s meeting of NATO foreign ministers — which was skipped by Landau’s boss Marco Rubio.

Landau, a longtime NATO skeptic who spoke first at the closed-door meeting, told ministers not to “bully” his country’s defense firms out of participating in Europe’s rearmament.

He then left the room soon after for other meetings, the diplomats said, though they noted that ministers only staying for a short time was not unusual.

A U.S. State Department official said: “Deputy Secretary Landau delivered two key messages. One is the is the need for Europe to turn its defense spending commitments into capabilities. The second is that protectionist and exclusionary policies that bully American companies out of the market undermines our collective defense.”

The EU has moved to scale up its historically depleted defense industry amid growing warnings by countries like Germany that Russia could attack Europe by the end of the decade.

Brussels has unveiled strategies in several legal proposals seeking to encourage local industry. Those efforts include the new €150 billion loans-for-arms SAFE program, but third countries like the U.S. can only supply a maximum of 35 percent of the value of weapons systems.

Landau’s broadside is the latest in a long list of blows by the current U.S. administration to its historic partners, which includes pressuring the EU into accepting a humiliating trade deal to stave off tariffs.

President Donald Trump has repeatedly slammed the bloc for treating the U.S. unfairly — while the EU has said Washington’s demands on trade were tantamount to blackmail. 

Landau’s comments are likely to leave a bitter taste in some capitals, coming as several European countries like Germany and Poland announced millions in new cash for a NATO-backed scheme that pays U.S. defense firms to supply critical weapons to Ukraine. In total, Europe and Canada have pledged $4 billion to the scheme, NATO chief Mark Rutte said Wednesday.

Trump has in the past questioned NATO’s security guarantees even if he has largely lauded the alliance’s efforts to ramp up defense spending to 5 percent of GDP by 2035. Over the summer Landau posted a deleted social media comment stating, “NATO is still a solution in search of a problem.”

Rubio’s absence marks the first time in more than two decades that Washington’s top diplomat hasn’t been present for a NATO ministerial meeting.

“No one’s shocked by the U.S. line that Europe shouldn’t be protectionist,” said one NATO diplomat, while adding: “But what did you expect … tact or nuance from the U.S.?”

NATO declined to comment.

This article has been updated.