target of 5% of gross domestic product. NATO leaders backed a big increase in defense spending on Wednesday that Trump had demanded, but Spain declared that it does not need to meet the goal and can meet its commitments by spending much less.

Trump called Spain's decision "very terrible" and vowed to force the country to make up the difference.

"We're negotiating with Spain on a trade deal. We're going to make them pay twice as much," Trump said.

As a member of the European Union, Spain does not negotiate directly with the United States on trade - the European Commission handles those talks for the entire 27-nation bloc.

Trump may have a hard time following through on his threat to punish Spain through a trade pact unless he gets language on the issue into a broader EU agreement. The Spanish Ministry of Economy declined to comment.