Rabbi Aharon Lichtenstein, head of the prestigious religious-Zionist Yeshivat Har Etzion and a leading disciple of the late Rav J. B. Soloveitchik, has posed a series of halachic questions to former Israeli Chief Rabbi Avraham Shapira.
Rav Shapira, one of the leading authorities for religious Zionists in Israel, ruled that soldiers must refuse orders to evacuate settlements. In a letter, Rav Lichtenstein questions him about the basis for this ruling. Rav Lichtenstein's letter has been publicized in the original Hebrew (RTF) and in English translation (RTF).
As opposed as I have been to the disengagement, I am inclined towards Rav Lichtenstein's approach to the halachic issues. The disengagement is now moot, but the issues at stake will remain relevant for some time to come.
Update: Some related links contributed by commentors Sharvul and NRK: