Nearly all steel contains small non-metallic inclusions, as these are essentially unavoidable by-products of current steelmaking practice. Intrinsic inclusions properties play a strong role in defining the influence they exert on the mechanical properties of steel; however, a second major factor of importance in this regard is the strength of the interface between the inclusion and the iron-based matrix in which they are contained. We present results of experiments where we measure, by means of direct in-situ micromechanical testing, the interfacial strength that the interface between silica inclusions and iron can sustain when subjected to tensile stress at room temperature. Micromechanical testing is conducted by means of bend beams carved parallel to a polished surface using focused ion beam milling. Strength values obtained for the silica-iron interface at room temperature come near one gigapascal, showing that spherical silicon oxide inclusions grown in iron can exhibit a very strong bond to the metal. Coupling experimental data with finite element simulations, we demonstrate that the interfacial strength values reported are not largely influenced by inherent focused-ion beam artifacts nor slight differences in beam aspect ratios. Microstructural observations, on the other hand, reveal the presence of debonded interfaces at selected locations in the as-produced samples. We show that the underlying cause for these debonds is likely to be the volumetric expansion that iron undergoes upon transforming from austenite to ferrite, implying in turn that there is a strong dependence on temperature and solicitation mode of the strength in this particular oxide-metal interface. This work was sponsored by the Swiss National Science Foundation, Grant No. 200021_182557.