Also, Israel WANTS this information out there to a large extent..a deterrent is worthless is your enemies don't know you possess it.
Lastly, during the Yom Kippur war, when Israel was completely surprised by the sneak Syrian/Egyptian attack..and USSR secretly supplied surface to air missiles all but decimated the IAF...PM GOlda Meir ordered 13 nuclear bombs attached to missiles and fighters..she also all but openly let the US and the western European nations know she was doing this.. Immediately after, Nixon authorized the airlift to resupply Israel. This included 40 F-4 Phantoms being flown to Israel. The US pilots landed at an IAF base, and while the planes were being refueld and armed, the US insignia was removed, and the Star of David painted on..and the planes took off an hour later..
I was just about to say the same thing. Everybody knows Israel has nukes...its the worst kept secret in the world. If WIKI knows Israel has nukes...and the Encyclopedia Britanica...than you can rest assured that the Arab's know...and they've known for decades....just like everyone else. I'm pretty sure the Soviets let that cat out the bag 30 ro 40 years ago.
She knew it was coming about 24 hours before but did not mobilize her reserves fearing (as usual) that they would be seen as the aggressor in American eyes.
So, they hesitated and got creamed in the beginning only to bounce back and obliterate Syrian and Egyptian forces.