Noem, who was asked about the Sunday night (Monday AEST) theft at the White House Easter Egg Roll, acknowledged the incident and said the matter has not been resolved.

The Secret Service, which provides security for Noem, reviewed security camera footage at the Capital Burger restaurant and saw an unknown white male wearing a medical mask steal her bag and leave the restaurant, a law enforcement source said.

The thief got away with Noem’s driver licence, medication, apartment keys, passport, DHS access badge, makeup bag, blank checks, and about $US3000 (about $4700) in cash.

The Secret Service launched an investigation to trace any use of Noem’s financial instruments, the person added.

“Her entire family was in town including her children and grandchildren – she was using the withdrawal to treat her family to dinner, activities, and Easter gifts,” a DHS spokesperson said.

Law enforcement experts have raised concerns about whether the incident, which involved a thief getting so close to a Cabinet official and then absconding with her belongings, may have been a lapse in security.

“This is a security breach that actually has high consequences, and it needs immediate and further review by the Secret Service and DHS, and other law enforcement partners,” said Jonathan Wackrow, a CNN law enforcement analyst and former Secret Service agent.

“If necessary, the Secret Service will need to make operational changes on how they deal with these types of private events moving forward,” Wackrow told CNN’s Kaitlan Collins on The Source.

He added that Noem remains “at higher risk for targeted threats, both by foreign and domestic actors, and just her public profile alone makes her a symbolic target”.