U.S. President Donald Trump criticized a U.K. deal over the Chagos Islands during his first-face-to-face meeting with Prime Minister Andy Burnham, dealing a blow to the British leader in an otherwise warm encounter.

Even as Trump on Tuesday complimented Burnham, praising him as a “natural business person” whom he could work with, the comments highlighted the challenging path the Labour leader faces in forging a smooth relationship with the U.S. president.

“I don’t support it. I think it’s terrible. It was a terrible deal,” Trump told reporters during a meeting on the sidelines of the U.N. General Assembly in New York. “Somebody has ownership that never showed up before after decades and centuries. I think it’s ridiculous. No, we were talking about that, and it’s strategically very important.”