  The debate on the nature of the gamma-ray emission from young supernova
remnants is still open. Ascribing such emission to hadronic rather than
leptonic processes would provide an evidence for the acceleration of protons
and nuclei, and this fact would fit with the very popular (but not proven)
paradigm that supernova remnants are the sources of Galactic cosmic rays. Here,
we discuss this issue with a particular focus on the best studied
gamma-ray-bright supernova remnant: RX~J1713.7-3946.
