I’m sorry for using figurative language on the internet where Dutch people are around. The full relevant part is below:

> Denmark isn’t an “ally.” An alliance is a mutual relationship. Denmark offers the U.S. nothing. It’s a country the size of Maryland…

In the construction “it’s not an X, it’s a Y,” X and Y are read in contrast to each other. Denmark isn’t an “ally” in the sense that it can’t offer meaningful aid to the U.S. in a war because it’s a tiny country. Obviously Denmark is an “ally” in the legal sense that we’re both part of NATO.