With passions running high on both sides in this year’s election and rising fears about Donald Trump’s impulsive nature and Hillary Clinton’s hawkish one, it’s hardly surprising that the “nuclear button” question has surfaced repeatedly throughout the campaign. In one of the more pointed exchanges of the first presidential debate, Hillary Clinton declared that Donald Trump lacked the mental composure for the job. “A man who can be provoked by a tweet,” she commented, “should not have his fingers anywhere near the nuclear codes.” Donald Trump has reciprocated by charging that Clinton is too prone to intervene abroad. “You’re going to end up in World War III over Syria,” he told reporters in Florida last month.