The U.S. warned the European Union about discriminating against American companies as the bloc’s national governments press ahead with plans for more defense cooperation, highlighting potential friction in trans-Atlantic relations.

The shot across the EU bow over defense procurement follows vocal demands by U.S. President Donald Trump for European members of the North Atlantic Treaty Organization to step up military spending.

In a bid to bolster Europe’s military strength, European governments have come up with 17 projects that mark the first use of EU-treaty provisions on enhanced security and defense cooperation among member countries. The project is dubbed PESCO.

“Certainly we do not want this to be a protectionist vehicle for the EU and we are going to watch carefully because, if that becomes the case, then it could splinter the strong security alliance that we have,” Kay Bailey Hutchison, the U.S. envoy to NATO, told reporters on Tuesday in Brussels. “We want the Europeans to have capabilities and strength, but not to fence off American products.”

Future Procurement

The comments signal a possible tussle when NATO defense ministers meet this week to discuss military budgets and deeper EU security cooperation. U.S. Defense Secretary James Mattis is scheduled to take part in the Feb. 14-15 gathering in the Belgian capital.

Hutchison sounded the alarm over possibly protectionist procurement in the future while praising allies including Germany for moving toward a pledge by NATO members to increase defense spending to at least 2 percent of gross domestic product by 2024.

The key in the EU’s joint-defense efforts is to act as a complement to NATO and to ensure a “very transparent sharing of information, sharing of opportunity,” she said.

“So far, there’s a fair process in procurement, we want to have a fair process,” Hutchison said. “It’s very important that there be transparency and openness in all of those areas where PESCO would be in a bidding process. That’s to be determined. It has not been set yet.”