War between a democracy and a terrorist organization is not symmetrical

Shajaiya neighbourhood encapsulates the challenge Israel faces in the Gaza conflict: It is crisscrossed with an elaborate network of underground bunkers and tunnels containing equipment for the manufacture of rockets, storage facilities for rockets and other weapons, and launching sites from which the rockets were fired at Israeli towns. It was a civilian area where Hamas embedded its most important military capabilities, precisely to encourage condemnation of Israel should the IDF be forced to fight there. How can Israel defend itself without being accused of violating the principle of proportionality?