Is it true that that’s what they claim? Yes.
Is it true that that is a truly rational and desirable aim if your goal is peace and prosperity? No.
I’m sure there are some Libertarians that do believe that. But (a) I see a difference between Libertarians and libertarians, (b) I don’t necessarily see this as a philosophical issue, so I’m not sure that being a libertarian is relevant.
See Trade & deficit