Six members of a Pennsylvania Air National Guard unit were sent to Washington earlier this month to help in aerial surveillance of protesters there, an operation now being investigated by the Air Force inspector general.

The New York Times first reported on that investigation and the involvement by members of Pennsylvania’s 148th Air Support Operations Squadron.

The Times cited a statement from the Air Force that the investigation was launched “following discussions with the secretary of defense about shared concerns,” after inquiries from lawmakers about whether the operation may have violated the civil liberties of protesters.

Defense Secretary Mark Esper has also ordered an “after-action review” of the deployment of National Guard units in states where protests took place.

Sara Goulet, a deputy press secretary for Gov. Tom Wolf, confirmed the six unit members were sent in response to a request for assistance from the District of Columbia National Guard.

Goulet said the guard members provided ground support for the aerial surveillance.

Ann Stefanak, chief of Air Force media operations, confirmed in an email Friday the existence of the investigation into the use of a National Guard RC-26 surveillance aircraft “in support of civil authorities.”

The 148th ASOS, based at Fort Indiantown Gap, provides “mission planning of direct combat air support and operate(s) and supervise(s) communications nets to support Air Force air resources and Army ground maneuver units,” according to the Pennsylvania National Guard.

Goulet said the call for assistance, known as a “guard-to-guard request,” was handled directly by the National Guard and Wolf was not involved.

Maj. Gen. Anthony J. Carrelli, the Pennsylvania National Guard’s adjutant general, reviews requests for support and decides if the personnel are needed in their home state instead.

“Then it becomes a decision for the governor,” Goulet said. “In this case, it was not.”

The six unit members spent “a matter of days” on the mission, said Goulet, adding that it was not longer than a week.

“Pennsylvania didn’t pay them,” Goulet said, noting the cost would be picked up by the requester.

The Times reported that Wolf had said publicly that he would not send troops from Pennsylvania to Washington “to bolster President Trump’s demand for 5,000 National Guard troops in the capital.”

But Lyndsay Kensinger, Wolf’s press secretary, on Friday said the governor had received a request earlier this month and had been considering it, based on the “significant resources deployed across Pennsylvania” at the time. Wolf did not flatly reject the request, Kensinger said.

Hundreds of National Guard troops were deployed to Philadelphia and other municipalities on June 1, after a third day of unrest, amid protests about the death of George Floyd at the hands of Minneapolis police officers. Peaceful demonstrations were marred by arson, looting, and street violence. Since then, protests in the city have peaceful.