BRUSSELS (AP) — The United States is warning the European Union not to use its deepened military cooperation as an excuse to protect Europe's defense industry, saying such practices could undermine NATO.

The U.S. ambassador to NATO, Kay Bailey Hutchison, said Tuesday that "we do not want this (cooperation) to be a protectionist vehicle for EU."

She said Washington is "going to watch carefully because if that becomes the case then it could splinter the strong security alliance that we have."

EU leaders — 22 of whose nations are also members of the U.S.-led NATO alliance — agreed last year to jointly develop or purchase military equipment like drones. Washington is concerned the bidding process might exclude U.S. firms.