Vice President Pence’s office threatened to retaliate against a reporter who revealed that Pence’s office had told journalists they would need masks for Pence’s visit to the Mayo Clinic — a requirement Pence himself did not follow.

Pence’s trip to the clinic Tuesday generated criticism after he was photographed without a surgical mask — the only person in the room not wearing one. The Minnesota clinic requires visitors to wear masks as a precaution against spreading the coronavirus.

Pence’s wife, Karen Pence, said in an interview with Fox News on Thursday that he was unaware of the mask policy until his visit was over.

But Steve Herman, who covers the White House for Voice of America, suggested that there was more to the story after Karen Pence’s interview.

“All of us who traveled with [Pence] were notified by the office of @VP the day before the trip that wearing of masks was required by the @MayoClinic and to prepare accordingly,” tweeted Herman, who covered the trip as part of his rotation as one of the pool reporters, who share information with other reporters in limited-space situations.

The tweet apparently enraged Pence’s staff, which told Herman that he had violated the off-the-record terms of a planning memo that had been sent to him and other reporters in advance of Pence’s trip.

Herman said he was notified by the White House Correspondents’ Association that Pence’s office had banned him from further travel on Air Force Two, although a spokesperson in Pence’s office later told VOA managers than any punishment was still under discussion, pending an apology from Herman or VOA.

VOA is continuing to talk with Pence’s staff, said Yolanda Lopez, the director of VOA’s news center. She said it wasn’t clear how the vice president intended to proceed.

Pence’s press secretary, Katie Miller, declined to comment.

The issue, according to people involved, is whether Herman’s tweet violated the off-the-record terms of a planning document sent via email Monday evening by the vice president’s office to reporters who planned to travel with Pence to the clinic.

A copy of the document obtained by The Washington Post explicitly stated that masks are required for the visit and instructed reporters to wear them. “Please note, the Mayo Clinic is requiring all individuals traveling with the VP wear masks,” the document said. “Please bring one to wear while on the trip.”

The directive confirms that Pence’s staff was well aware of the need for masks, raising the possibility that none of his aides had alerted him to the requirement or that Pence had intentionally flouted it, perhaps to avoid being photographed in a mask. (Pence himself told reporters after the visit that because he doesn’t have the coronavirus — he is tested frequently — he decided he could “speak to these researchers, these incredible health-care personnel, and look them in the eye and say thank you.”)

However, the planning document is marked, “OFF THE RECORD AND FOR PLANNING PURPOSES ONLY.” The off-the-record designation is standard for such logistical memos, indicating reporters are obligated not to publish or report the information. The White House typically keeps planning information confidential to maintain security for official trips.

But there’s some question about how long the obligation lasts — whether it is permanent or only applies to the period before and during the trip.

Herman’s tweet came nearly 48 hours after the vice president’s trip had ended, suggesting the vice president’s staff was more embarrassed by the disclosure than concerned about security.

“My tweet speaks for itself,” Herman said in a statement. “We always have and will strictly adhere to keeping off the record any White House communications to reporters for planning purposes involving logistics that have security implications prior to events. . . . All White House pool reporters, including myself and my VOA colleagues, take this very seriously.”

As is, the vice president’s office took no action against another reporter, Gordon Lubold of the Wall Street Journal, who traveled with Pence and tweeted something similar to Herman’s tweet Thursday. “Everyone in the entire Mayo Clinic had a mask on, everyone, and we were all told the day before we had to wear a mask if we entered the clinic,” Lubold tweeted.

In a now-deleted tweet, the clinic said it had alerted Pence to its mask policy before his visit. A later statement from the clinic said only that it had informed Pence’s office of the policy, not Pence personally.

Voice of America is a government-funded but independent news agency that has lately been the object of White House criticism. The Trump administration accused VOA this month of promoting Chinese government propaganda in its reporting about the coronavirus. The VOA’s director, Amanda Bennett, has defended its independence.

On Thursday, Pence wore a mask as he toured a General Motors auto plant in Indiana that has been converted into a factory making ventilators for hospitals around the country.