"There's about four minutes between the order being given and the people responsible for launching nuclear weapons to do so," Clinton said, explaining the quick decision-making required of a commander in chief and questioning Donald Trump's fitness for the job.
"And that's why 10 people who have had that awesome responsibility have come out and, in an unprecedented way, said they would not trust Donald Trump with the nuclear codes or to have his finger on the nuclear button," she continued.
But questions soon began to emerge about whether Clinton was too specific in her description of nuclear launch times and had perhaps revealed something she learned in a classified setting.
A Clinton campaign aide said the information didn't come from a classified briefing, pointing to multiple instances when similar information has been disclosed in public or through open source material.
In the July 2001 report "Minuteman Weapon System History and Description," authors from Hill Air Force Base in Utah discuss the amount of time needed. The "process of presidential authentication with the Pentagon war room and the formatting of a launch order by the war room prior to its dissemination to the Minuteman firing crews would add another 1 minute or so, for a grand total of 4-5 minutes."
And Joseph Cirincione, president of the Ploughshares Fund, which specializes in nuclear issues, tweeted out public references to the same assertions regarding timing.
But even if the information is publicly available, those with clearances cannot reveal anything they learn in a classified setting.
Asked about the sensitivity of this specific information, US Strategic Command, which oversees the US nuclear arsenal, declined to weigh in on the specifics.
"We do not disclose operational timelines, but we do work to provide the President as much decision space as possible," Capt. Brook DeWalt, chief spokesperson for Strategic Command, told CNN in a statement.
Defense Secretary Ash Carter, who appeared at news conference with his South Korean counterpart Thursday, demurred on a similar question about whether such information was classified, saying that the question was "cast in terms of the ongoing presidential campaign."