While Mnuchin denied he wanted the government to pay for his personal travel, and said the story had been "misreported," the news was only the latest embarrassment for the notably wealthy Treasury secretary, a former investor and Hollywood mogul.
His actress wife Louise Linton recently apologized for lashing out on social media at a woman who criticized her for advertising the high fashion brands she was wearing during an official trip with Mnuchin.
ABC News reported Wednesday that Mnuchin requested the use of a US Air Force plane, which costs $25,000 an hour to operate, to take the newlywed couple to Scotland, France and Italy following their summer wedding, which President Donald Trump attended.
Mnuchin ultimately did not use the jet and he stressed Thursday that Treasury only made the request as one option to allow him to send and receive sensitive national security communications while traveling.
"I probably spend 50 percent of my time on national security issues," including matters involving North Korea and Iran, he told an event organized by Politico, a Washington political newsletter.
"At the time, my staff wanted to make sure that I constantly had access to secure communications and secure information."
Mnuchin said the military aircraft would have been used as "a portable office," but the request was withdrawn when another option was found.
"Let me just set the record straight," he said. "The government has never paid for any of my personal travel."
Mnuchin also faced scrutiny following a trip last month to Kentucky, when his wife traveled with him to visit the US gold reserve at Fort Knox, on the day of the total eclipse of the sun.
Linton posted a photo of herself descending from an government plane on the social media network Instagram, tagging the brands of designer clothing and accessories she wore.
She later apologized for her condescending and "highly insensitive" responses to a woman who criticized her for appearing to use taxpayer funds for a vacation.
The Treasury Department said the couple reimbursed taxpayers for the cost of Linton's travel, although the department's inspector general has opened a review of the trip.
Mnuchin himself had to admit his mistake in March for plugging the animated movie "Lego Batman," which he produced prior to joining Trump's cabinet, since government officials are prohibited from using their positions to enrich themselves.
A former Goldman Sachs executive, Hollywood producer and banker, Mnuchin is a one of a cadre of wealthy Trump administration officials. Fortune magazine estimates Mnuchin's net worth is as high as $500 million.
During Senate confirmation, he faced awkward questions about previously undisclosed offshore investment firms and real estate holdings of about $100 million.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)