A good question. I have no idea why Israel wants or needs nuclear weapons, if anything they are generally a liability, militarily and politically, for them.
I can see how they might have seemed a necessary deterrent balancing conventional military inequities perceived in the '60s and '70s, but this ain't then, and their current conventional military capabilities make them more than equal to any combination of potential enemies and coalitions.
So you're stating that all the regional countries don't have conventional military advantages over Israel? Its readily apparent that the combined forces of the regional powers will always have a conventional advantage over Israel and since there continue to exist hostile elements within these countries that hold sway over the populace, ie voting power, there will always be this threat. If the regional powers and their constituents do a complete 180, then I would see where this need for nuclear ambiguity and power overall would be declared pointless and an unneccesary liability.
Nuclear power always carries liabilities, whether in the UK, US, India, Pakistan or Israel (albeit more with Pakistan than any other country). As things stand currently, removing the nuclear power capabilities of Israel would prove to be less beneficial and more of a liability to Israel than actually having them.
Personally, I believe the UK has a significantly less justification for its nuclear program and to have a nuclear sub running around the sea with 48 nuclear warheads, than Israel to have an ambiguous stance when it comes to its nuclear weapons capability. And contrary to NPT standards, the UK is improving its nuclear weapons capabilties.
The last decade or two, Israeli nuclear capability seems to have been used more to intimidate regional and global political issues than as a purely defensive deterrent to annhilation. I certainly don't believe that Israel is a rogue nation, but within the larger international community of nations they are much more shifted to that end of the spectrum than most major nuclear powers, and in my opinion the situation has worsened over the last couple of decades rather than improved.
As Giz already asked, where does this intimidation lie? And what political issues are you referring to? Iran? I'm sure Iran is not complaining after the Osirak reactor was destroyed in 1980 (after Iran tried and failed months before) of their loving neighbor Iraq. But then again, this was more of an actual and immediate threat since it dealt with Saddam who has quite the extensive history of threatening its neighbors, actually using non-conventional weaponry against his neighbors and his own people, and financing and proliferation to terrorist groups.
This ties in with the above as well, since the need for a deterrance still exists even if proxy warfare is the centerpiece of countries like Iran and Syria more so than the threat of a (yet another) massive invasion by Israel's neighbors. Removing Israel's nuclear capabilities would do next to nothing in deterring Iran's and Syria's pursuit of nuclear power. Israel's position of nuclear ambiguity has not forced countries like Jordan, Egypt, and Saudi Arabia to pursue a nuclear program either, since, and correct me if I'm wrong, these countries don't see Israel's nuclear power as a threat to their country's security for the last 40+ years. Iran and Syria, on the other hand, do, hence the aforementioned countries desire to develop their own nuclear programs. No coincidence there.
If it helps, I don't consider any of these nations to have valid and reasonable reasons to be non-signatories to the NPT, or to be excluded from international law, treaties and standards, nor with regards to US policy toward nations in violation of these laws treaties and standards. Of course, we've got a lot of hypocrisy to get rid of if we are going to achieve any consistency with regards to this type of stance.
Signatories of NPT hold little sway over non-NPT countries like India and Israel in terms of their arguments against non-NPT countries (except Pakistan to a degree) for not joining the NPT community. NPT countries have not abided or solved the same issues that were brought up when NPT was first put together in the 1970s, apart from decreasing the nuclear warheads stored from several thousand to a few thousand, and yes, ceasing with physical testing (which Israel doesn't do either), rather opting for virtual, supercomputer testing of its nuclear weapons and tweaking their physical weapons from these results. An additional issue with NPT signatories are presented with recently is the issue of security over their existing nuclear materials, which Israel doesn't have an issue with. US has several hundred nuclear weapons and storage facilities in EU countries as well.
US's arguments against non-NPT countries like Israel would thus seem to be a futile practice in hypocrisy which I would guess is one of the reasons why the US refuses to do so.
I'm not sure that this article adds much to the discussion, especially with regards to the Israeli weapons program, but would be interested in how you link the two.
Pretty straightforward. The threats presented in that article as perceived by India are the same threats that Israel sees as a justification for its nuclear program. Short of a public display of power by detonating nukes by Israel, the threat of Iran and Syria (to which Pakistan, China, and North Korea have been willing benefactors to, from providing nuclear warhead capable ballistic missiles, crude nuclear weapon designs, nuclear material refining/weaponizing technology, etc.) can be roughly equated to the threats China and Pakistan posed to India in the non-conventional sense.
Judging by the fact that India is almost 160 times larger than Israel, non-conventional threats, predominantly with irradiated (dirty) and biological bombs, would do significantly more damage to Israel compared to India. The nuclear deterrance of Israel against Iranian/Syrian funded/trained/financed proxy terrorist groups crossing the threshold from conventional to non-conventional is enough just cause in Israel keeping this deterrance and thus its position of nuclear ambiguity.