Because they have enough nukes to kill the planet and if they think the will fall they follow in the footsteps of Samson and bring the Temple down upon themselves and everyone else. That's the only reason anyone really needs as to why.
Another reason Is everyone sat by and watched as Germany was shitting on the Jewish people and others in Europe and did nothing until the Brits got fucked with. So everyone feels super guilty and gives them a Nation which incites so many goddamned wars that they gave them Nukes which made them a world power.