What bluff? Israel were going to use their nukes had U.S not resupplied then  , they were getting owned and were finished without U.S help. The story of their entire history basically.
What about Iran?
		
		
	 
Fair enough, in part....."bluff" was not the best choice of words.....certainly Israel would have used nukes if there had been no other alternative.
The game was to get re-supplied.
Israel knew the Yom Kippur War was coming, but made a reasoned decision to not strike pre-emptively because of the trouble it got in for the 1967 strikes.......
What the Yom Kippur War proved is that Israel MUST strike pre-emptively, if it is to defend itself.  The place is so so tiny, it could be over run in a matter of a few hours........and it can not mobilize, take up defensive positions and wait, because every male is a soldier, and the nation has to shut down to mobilize.  That can't last long.
Every war Israel fights it has to fight quickly, and decisively.  That is the reality.
The US only re-supplied them, they kicked Arab arse all by themselves, yet again.
Just to show you what Israel was up against::
1967 War:
Israel: 
50,000 troops
214,000 reserves
300 combat aircraft
800 tanks
[2] Total troops: 264,000
100,000 deployed
Egypt, Syria, Jordan, Iraq
Egypt: 240,000 troops
Syria, Jordan, and Iraq: 307,000 troops
957 combat aircraft
2,504 tanks
[2] Total troops: 547,000
240,000 deployed
http://en.wikipedia.org/wiki/Six-Day_War
The enemy had twice the available troops, three times the aircraft, and three times the tanks.
the 1973 Yom Kippur War
Israel
375,000
[8]–415,000 troops,
1,700 tanks,
[18]
3,000 armored carriers,
945 artillery units,
[11]
440 combat aircraft
The Arabs
Egypt: 650,000
[8]–800,000
[9] troops, 1,700 tanks (1,020 crossed),
[10] 2,400 armored carriers, 1,120 artillery units,
[11] 400 combat aircraft, 140 helicopters,
[12] 104 Navy vessels, 150 surface to air missile batteries (62 in the front line)
[13]
Syria: 150,000
[8] troops, 1,200 tanks, 800–900 armored carriers, 600 artillery units,
[11][14][15]
Expeditionary Forces*: 100,000 troops,
[8] 500-670 tanks,
[16][17] 700 armored carriers
[16]
http://en.wikipedia.org/wiki/Yom_Kippur_War
The arabs had 2 1/2 times as many soldiers, half again the number of tanks, more artillery and APCs.....and more aircraft.
If Israel had not had the buffer zones of the Sinai and the Golan Heights, the nation would have been forced to go nuclear.