^ This. The Federation lacked the mean to simply throw the Cardassians off of Bajor. The Federation had been fighting a multi-year long war with the Cardassians over an area of territorial expansion they both wanted, and the Cardassians were far from push overs in the military realm.
the fact that the Federation was in a war against Bajor's enemy at the time makes it stupider that they didn't intervene to help them. In war, you ally yourself with those who are fighting your opponent. The Federation should have at least been supplying the Bajorans with weapons or something like that.