Ehud Israel has publicly several times threatened to bomb the enemies to stone age. Where is the guaranty that Israel doesn't use the nukes? A promise that we do not use them first is as convincing as Israeli promises to reduce the roadblocks on West Bank, no more settlements, make Palestinian economy better etc.
13 security personnel killed in Iraq suicide bombing (DPA)
from the article: Poll: 72% of Israelis back use of nuclear arms in certain circumstances