Peter Juul makes the case:
Israel’s nuclear deterrent is shrouded in secrecy, but it is estimated to have between 100 and 200 nuclear warheads. Like the United States, Israel’s nuclear delivery forces are structured to form a “triad” of air, land, and sea-based systems. Israel’s long-range F-15I and F-16I strike aircraft are believed to be nuclear capable, and have the range to reach targets in Iran without refueling. More central to Israel’s nuclear forces are its Jericho-series of ballistic missiles. Israel is estimated to have between 50 and 100 Jericho II missiles with a range between 1,500 kilometers and 3,000 kilometers, and in January tested a new 4,000 kilometer-range missile. This new missile puts all of Iran in Israel’s nuclear reach. Finally, Israel’s three Dolphin-class submarines are reportedly capable of firing Harpoon missiles modified to carry nuclear warheads, and in 2000 Israel reportedly tested a 1,500 kilometer range cruise missile from one of its submarines. Two more submarines are on order from Germany. Israel therefore has a mature nuclear deterrent likely capable of launching a second strike against adversaries.
I’ll agree this far; Israel has now and will maintain for the foreseeable future a secure second strike capability vis-a-vis Iran, but that has more to do with the deficiencies of Iran’s program than with the strength of Israel’s. The reason I caveat is that the Dolphin class submarines, while fine and and capable warships, aren’t large enough or numerous enough to provide secure second strike to the degree enjoyed by France, the UK, Russia, or the US. The French Triomphants and the British Vanguards are each 4-6 times the size of the Dolphins, and carry 16 MIRVed ballistic missiles. I can’t imagine that the Israelis would be able to squeeze more than a very small handful of nuclear warheads onto a Dolphin, or keep more than one boat on continuous patrol. What this means in practical terms is that while Britain and France have roughly 180 or so warheads on continuous submarine patrol, the Israelis have maybe about 5. Now, five or so is probably enough, but you’d like to have more for a genuine deterrent relationship.
Of course, since Iran can’t provide any serious threat to the land or air based components of Israel’s nuclear triad, this doesn’t mean very much in practical terms.