In an interview with Fox News host Tucker Carlson, President Trump said he thought having to protect NATO nations that “weren’t paying” was “very unfair.” When Carlson asked Trump why his son should have to “go to Montenegro to defend it from attack,” the president replied, “I understand what you’re saying, I’ve asked the same question.” Being a NATO member nation obligates participants to come to the aid of another member when they are attacked. In the interview, Trump claimed that the U.S. pays up to “90 percent of the costs to defend Europe” within this alliance between states. He continued: “It was very unfair, they weren’t paying. Not only are we paying for most of it but they weren’t even paying and we’re protecting them. Add that to your little equation on Montenegro.” The remark comes after a contentious NATO summit concluded in Helsinki last week and a controversial meeting and press conference with Russian President Vladimir Putin—prompting European politicians to look elsewhere in the United States for assurances.