"If Iran were to acquire nuclear weapons, it could give a nuclear umbrella to terrorists, or worse it could actually give terrorists nuclear weapons, and that would put us all in grave peril."

VOA: special.2009.05.23

"The U.S. nuclear umbrella alone is no longer enough to assure our security, " says Defense Minister Yoshinori Ohno.

FORBES: The Front Line

In return, America could extend a nuclear umbrella to Israel to put it at ease about nuclear attacks.

ECONOMIST: Higher risks

Like some European states, Britain could limit itself to defending its national territory while sheltering under NATO and America's nuclear umbrella.

ECONOMIST: Britain's armed forces