R. Jeffrey Saks pointed me to a number of statements by R. Joseph B. Soloveitchik on this topic in his recently published letters, Community, Covenant and Commitment: Selected Letters and Communications:
"I never declared any opinion on issues [of territorial compromise in Israel] that according to my view only those Jews who are defending the borders of the land with their blood have a right to deal with." (p. 231)
"[However,] since I am not a resident of Eretz Yisrael (a point I emphasized), it is impossible for me to publicize my opinion. Diaspora Jews should not involve themselves in the internal affairs in Israel." (p. 198)
"[Q:] Do you support the peace proposal of Dr. Henry Kisssinger...?
[A:] I do not live in Eretz Yisrael and I have no right to express my opinion on these matters." (p. 235)
(An additional thanks goes to Joel Rich who also brought these to my attention)