"fears that a cloud of Soviet bombers could appear at any time, armed with nuclear bombs "

This assertion needs a reference. The word I find particularly dubious is "cloud" implying MANY. The Soviets had only conducted a single nuclear test by the time of this incident. While, on that basis, they might have been conduct one or two atomic bomb attacks the way the US did in 1945, it is highly dubious anyone feared a more massive attack.

Of course, "one or two", as the citizens of HIroshima and Nagasaki know, is horrendous enough. No need to exaggerate that by citing imaginary "clouds"!