What signals the "official" start of WW3?

I think WW3 will begin when Jerusalem is surrounded by armies.

That is a good question. im doing some research up on this topic, and ill get back to you... but im thinking that maybe it already has started, and hasnt ever ended.. maybe its just a slow long and silent war...

ok, i did a little bit of reasearch for this so here goes:

1. Vietnam
   
2. Cold war & the fall of the solviet union
   
3. 911 (twin towers/pentagon/pennsylvania)
   
4. War in Afganistan and Iraq
   
5. Desert Storm
   
6. Anthrax attacks
   
7. West nile viris theory (possibly man made and used for biological warfare)
   
8. Police states across the world
   
9. Bay of pigs invasion
   
10. Oklahoma city bombing
    
11. Gov't's Black projects and "secret military establishments"
    
12. North Korea invading South Korea
    
13. nuclear technology being born
    
14. Mercury poisoning in Minamaka Bay, Japan in 1953
    
15. Fidel Castro invading Havana
    
16. Solviets shooting down spy plane capturing CIA operative Francis Gary Powers
    
17. US invasion of Cambodia and Laos
    
18. Iraqi and Iran War back in 80'
    
19. brittan and argentina go to war over fawkland Islands in 82'
    
20. The U.S.S warship Vincennes shoots down an iraqi airliner
    

Well, thats some of the stuff i could find over what has happened from about the time that WW2 ended. maybe we are at war, maybe not.. you draw your own conclusions.. but i really think that we may not be at war at all.. cause if you look at the two other world wars, it involved a lot of countries mostly all at one single time.
Well, PEACE
-Agent23212

I was thinking about this the other day.

Im guessing the next World War would be when countries start hitting each other with nukes,its inevitable.

Also heres what i think constitutes a World War

World War Definition:

A World War is a military conflict spanning more than 2 continents, in which at least 20 major countries participate in an attack against a common enemy, and which has the attention of the man-in-the-street due to the significant loss of life.

With that definition, we can agree that WW1 and WW2 were in fact World Wars (both wars involved some degree of participation from most of the world's then existing countries: Britain, France, Germany, Italy, Japan, the United States and the Soviet Union), and that we are very close to achieving World War 3.

The only requirement left to fulfil the start of WW3 is that of a military conflict spanning more than 2 continents.

As soon as Israel attacks Palestine, or North Korea attacks South Korea or the US, or China invades Taiwan, we will have the next World War well underway.

Heres the countries who took part in the last World War

World War II - a war between the Allies

Australia,
Belgium, Bolivia, Brazil,
Canada, China, Colombia, Costa Rica, Cuba, Czechoslovakia,
Dominican Republic,
El Salvador, Ethiopia,
France,
Greece, Guatemala,
Haiti, Honduras,
India, Iran, Iraq,
Luxembourg,
Mexico,
Netherlands, New Zealand, Nicaragua, Norway,
Panama, Philippines, Poland,
South Africa,
United Kingdom, United States, USSR,
Yugoslavia

and the Axis

Albania, Bulgaria, Finland, Germany, Hungary, Italy, Japan, Rumania, Slovakia, Thailand from 1939 to 1945

Many people do consider that we are in WWIII already and it started just over a year after 9/11, but all the major news networks have avoided any reminiscent of World War.

Hope this helps.