Nuclear triad
Israel is known to have nuclear-capable aircraft and land-base missiles, with the addition of nuclear-armed submarines this would mean that they now have a full triad of land-, air-, and sea-based nuclear delivery systems some of which would be invulnerable to a first strike by an enemy for the first time in their country's history. No other nation in the Middle East in known to be in possession of nuclear weapons, even though Iran, Iraq, Syria and Libya have started development programs that were never completed.
Views on the nuclear program of Iran
Iranian politicians compare its treatment as a signatory to the NPT with three nuclear-armed nations that have not signed the NPT: Israel, India, and Pakistan. India and Pakistan developed an indigenous nuclear weapons capability, and it is widely suspected that Israel has as well: Israel by 1966, India by 1974, and Pakistan by 1990.