1) So what if Hamas agrees to a cease-fire when the rest of the Arab world (and other terror groups) do not? 2) Historically speaking, their promises are worth nothing. Hamas used the beach explosion which their own people caused as an excuse to break the last cease-fire. Furthermore, Islam allows one to break promises to infidels (that's us, silly!) so again their promises are worthless. Israel does not need the approval of terrorists to exist. We should reward peace overtures and punish terrorism. So long as terrorism pays off it'll continue.
from the article: Haniyeh advisor: Attacks on Israel don't serve Hamas