President Trump will push North Atlantic Treaty Organization allies to meet their defense spending obligations on Thursday when he attends his first NATO summit in Brussels, Secretary of State Rex Tillerson said on Wednesday.

“As the president has said, he really wants participating NATO members to step up and fully meet their obligations of the burden sharing,” Tillerson told reporters aboard Air Force One. “Two percent of GDP was a target they all agreed to. I think you can expect the president to be very tough on them, saying: ‘Look, the U.S. is spending 4 percent. We’re doing a lot. The American people are doing a lot for your security for our joint security. You need to make sure you’re doing your share for your own security as well.'”