Following up on this post, I saw that the Tzitz Eliezer, in his Hilkhos Medinah vol. 2 5:7:2, agrees with R. Shaul Yisraeli's position that even the Rambam agrees that the rule about laying a siege only applies to a permitted war and not a mandatory war. I'm surprised that neither R. Yisraeli nor R. Goren quoted this.
And following up on this post regarding triage, I saw in the book Hatzalah Ke-Halakhah (no. 12) about halakhic questions that arise in the Hatzalah Volunteer Ambulance organization, that the author follows R. Moshe Feinstein's position and not that of the Tzitz Eliezer.