Using nuclear resonant scattering of synchrotron radiation and density functional theory calculations we have resolved the magnetic properties of the different Fe phases present at the Fe/NiO (001) interface, an epitaxial ferromagnetic/antiferromagnetic system. We have detected the presence of an interfacial antiferromagnetic FeO-like phase with a significantly increased magnetic moment compared to the case of a sharp interface. Already a few atomic layers above the interface, the Fe atoms have a bulk-like metallic character and the reversal of their magnetization is strongly influenced by the antiferromagnetic layer.