Note: This story was updated on Nov. 3, 2021.

WASHINGTON ― A group of close U.S. military allies worried a legislative proposal to boost to “Buy American” requirements will upend longstanding defense trade pacts is asking Senate lawmakers to scuttle the measure — or at least make it friendlier.

A group of 25 foreign military attachés whose countries have special reciprocal trade agreements with the Pentagon wrote Oct. 28 to Senate Armed Services Committee Chairman Jack Reed, D-R.I., and ranking member Jim Inhofe, R-Okla., to ask that they oppose the language during eventual talks to reach a compromise 2022 defense policy bill. The group includes Canada, France, Germany and the U.K.

It’s the latest flashpoint in the fight over Democratic efforts to boost domestic manufacturing by strengthening “Buy American” requirements, which apply to about a third of the $600 billion in goods and services the federal government buys each year.

Since U.S. President Joe Biden took executive action during his first week in office, the House-passed 2022 National Defense Authorization Act contained language from Rep. Donald Norcross, D-N.J., to codify that boost into law, and Sen. Tammy Duckworth, D-Ill., proposed similar language as an amendment to the Senate’s NDAA.

Existing federal laws make “Buy American” exemptions available for countries that have reciprocal defense trade agreements (plus Latvia and Estonia) ― and for the Pentagon to standardize equipment with NATO members and buy equipment overseas that is unavailable or too expensive from domestic suppliers.

Still, some allies are opposed to the changes. In an interview with Defense News on Tuesday, Pieter-Henk Schroor ― a Dutch defense cooperation attaché who chairs the Defense Memorandum of Understanding Attachés Group and sent the letter ― argued that unraveling defense production agreements will hurt some weapons programs or erode America’s multibillion-dollar defense trade surplus. Some allies who spend heavily on U.S. weapons do so because their countries are allowed to help build those weapons, he said.

“If that incentive would no longer exist, simply because our defense industries would no longer be welcome in U.S. markets, of course that would also have an effect on our incentive to buy here,” Schroor said. “Especially European countries will start looking at alternatives and would be far more interested than they are currently to buy European.”

“If there would not be a defense trade with DMAG countries to the level that exists today, that would really damage economic growth in the U.S. or at least cost jobs in the U.S.,” he added.

Asked about the matter Tuesday, Reed said in a brief hallway interview he supports Duckworth’s proposed amendment but also said that the intent behind the Democrats’ “Buy American” push is to work with allies.

“What we want to do with the supply chain is make sure it’s in secure hands, which means some of our closest allies also ― not just exclusively the United States,” Reed said. “It would technically be very difficult [to untangle U.S. and allied defense supply chains] anyway.”

Inhofe said the U.S. would be unable to access all the equipment it needs under what he called a “severe ‘Buy America’ provision.”

The defense attaché group made a similar request over Norcross’s “Buy American” proposal last year, and it was later dropped from that year’s NDAA. This year, Duckworth’s amendment, if it is taken up and passed, would strengthen the hand of “Buy American” proponents going into NDAA negotiations.

Though current law exempts reciprocal trade agreements and more, the group of defense attachés would like to see the new proposal from Norcross be amended to include an explicit protection, if the proposal cannot be excised entirely.

Schroor said he’d been told the Norcross provision is meant to target China, not allies, but he said that it would go a long way toward soothing allies’ concerns if the legislation made that clear.

America’s largest defense trade union, the International Association of Machinists and Aerospace Workers, backs both legislative proposals.

“This amendment will not only grow our industrial base and help give thousands of working Americans the opportunity to improve their lives and communities, but it will increase the number of domestic manufacturers throughout the country,” Robert Martinez Jr., the union’s president, said in a statement Oct. 29.

Some critics of the “Buy American” push are especially concerned because the Biden administration is undertaking broader efforts to strengthen domestic supply chains for certain goods and add U.S. manufacturing jobs. Biden and other high-level officials in his administration have said they will look to work with international partners, but some allies hear a mixed message.

“We hear about reshoring of economic activities ... and in that same vein that close relationships with allies and partners will be supported. But all in all, it’s not clear enough to us if we will be included or not in the complete overhaul of supply chains,” Schroor said. “Are they looking at the domestic defense industrial base or the defense industrial base with partners?”

Joe Gould was the senior Pentagon reporter for Defense News, covering the intersection of national security policy, politics and the defense industry. He had previously served as Congress reporter.

More In Congress