Until they were threatened by a lawsuit, the Air Force would not agree; implies that the Air Force were obstinate and that an extreme measure was required. " (dummy "it") is an idiomatic pattern used to describe what was required to achieve some result. "it caused being threatened by a lawsuit" is not correct English.
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SweetFreedomThanks.How to edit "it caused being threatened by a lawsuit" into proper English then?I don't see an obvious way to do that within this context.