unless this were the ww3, in more hot problems there have been not a nuclear bomb involved...
as i said, Israel will only use the bomb in two scenarios:
first: Israel is close to be destroyed, and feels that the only way to survive is to use nuclear weapons, in the countrys sorrounding Israel, Israel will use small nukes, and probably Neutron bombs, so there will be the smallest amount of radiation left.
second: Israel is destroyed, the Sampson option is activated, and 100-600(depends on witch estimation your going with) are launched at almost every country in the ME and probably Russia.
Israel was on nuclear alert only 3 times:
1967- in the weeks before the six day war Israel built 2 primative nukes, Israel feared that she will not be able to survive a war in 3 fronts.
1973- in the Yum Kippor war Israel assigned 4 squadrons of F-4's to be in 24h standby, and had every missile launching platform operational. Israel demmanded that the U.S supply her army or she will use nuclear weapons( in the second day of the war Israel already sent F-4's with nuclear bombs but had called them back).
1991- in the first day of the Gulf war an american satelite showed 20 launchers aimed at Iraq and other arab countrys, after it was known that the SCUD missiles were not with chimical weapons the launchers got back to thier secret hiding places.