Excluding non-Arab Pakistan, which is itself hardly a pillar of stability these days, none of Israel's extant Jihadist foes has "the bomb." However, acting together, and in a determined collaboration (had they been capable of cooperation), they could still have carried out intolerable and lethal assaults upon the Jewish state.
An integral part of Israel's multilayered security system lies in effective ballistic missile defenses, primarily, the Arrow or "Hetz." Yet, even the well-regarded and successfully-tested Arrow, augmented by the newer and shorter-range operations of "Iron Dome," could never achieve a sufficiently high probability of intercept to protect Israeli civilians. No system of missile defense can ever be entirely leak proof, and even a single incoming nuclear missile that somehow managed to penetrate Arrow or corollary defenses could conceivably kill tens or perhaps hundreds of thousands of Israelis. This reality could potentially be less consequential if Israel's continuing reliance on deliberate ambiguity were suitably altered.
The current Israeli policy of an undeclared nuclear capacity is highly unlikely to work indefinitely. Leaving aside a Jihadist takeover of nuclear Pakistan, the most obviously unacceptable "leakage" threat would come from a nuclear Iran. To be effectively deterred, a newly-nuclear Iran would need convincing assurance that Israel's atomic weapons were both (1)invulnerable and (2) penetration-capable.
Any Iranian judgments about Israel's capability and willingness to retaliate with nuclear weapons would then depend largely upon some prior Iranian knowledge of these weapons, including their degree of protection from surprise attack, as well as Israel's capacity to "punch-through" all pertinent Iranian active and passive defenses.
A nuclear weapons-capable Iran may already be a fait accompli. For whatever reasons, neither the "international community" in general, nor Israel in particular, has managed to create sufficient credibility concerning timely preemptive action. Such a critical defensive action would require complex operational capabilities, and could generate Iranian counter actions that would have a very significant impact on the entire Middle East. Nevertheless, from a purely legal standpoint, such preemptive postures could be justified under the codified and authoritative criteria of anticipatory self defense under international law.
It is likely that Israel has already undertaken some very impressive and original steps in cyberdefense and cyberwar, but even the most remarkable efforts in this direction would not be enough to stop Iran altogether. The so-called "sanctions" sequentially leveled at Tehran over the years have had an economic impact, but they have had no determinable impact in halting Iranian nuclearization. In fact, it is perhaps more likely that sanctions have actually increased Iran's desire to obtain nuclear weapons.
A nuclear Iran could decide to share some of its nuclear components and materials with Hezbollah, or with another kindred terrorist group. To prevent this, Jerusalem would need to convince Iran, inter alia, that Israel possesses a range of distinctly usable nuclear options. Israeli nuclear ambiguity could be loosened by releasing certain very general information regarding the availability and survivability of appropriately low-yield weapons.
Israel should now be calculating (vis-à-vis a nuclear Iran) the exact extent of subtlety with which it should consider communicating key portions of its nuclear positions. Naturally, Israel should never reveal any very specific information about its nuclear strategy, hardening, or yield-related capabilities.
An Israeli move from ambiguity to disclosure would not help in the case of an irrational nuclear enemy. It is possible that certain elements of Iranian leadership might subscribe to certain end-times visions of a Shi'ite apocalypse. By definition, such an enemy would not value its own continued national survival more highly than every other preference or combination of preferences.