Investigation into military aircraft to monitor protests

The Air Force inspector general is investigating the use of military aircraft to monitor protests across the United States this month in the wake of George Floyd's death.

"Following discussions with the secretary of defense about shared concerns, the secretary of the Air Force is conducting an investigation into the use of Air National Guard RC-26 aircraft to support civil authorities during recent protest activity in U.S. cities," Brig. Gen. Patrick Ryder, the chief Air Force spokesman, told ABC News in a statement. "The investigation is being led by the Air Force inspector general. It would be inappropriate to comment further at this time due to the ongoing nature of the investigation."

The New York Times first reported the news of the probe.

The move comes just days after Joseph Kernan, the under secretary of defense for intelligence, confirmed to Congress that no military intelligence agencies had spied on Americans during the wave of nationwide protests, nor were they asked to do so by the Trump administration.

In a letter to House Intelligence Committee Chairman Adam Schiff, who had inquired about the use of military intelligence, Kernan said that "a recent effort" by the Defense Intelligence Agency "to establish an internal coordination group focused on potential foreign interference associated with the protests was mischaracterized" in media reports as being "potentially focused on domestic political activities of U.S. persons."

Earlier this month, more than 5,000 National Guard members from dozens of states were deployed to the nation's capital while thousands more were sent to cities across the country to help local law enforcement quell the civil unrest. The wave of demonstrations, some of which ended in violence, were prompted by the May 25 killing of Floyd, a 46-year-old unarmed black man who died in Minneapolis shortly after a white police officer was filmed kneeling on his neck as three other officers stood by.

On June 4, Sen. Chris Murphy, D-Conn., took to Twitter to demand answers after an Air National Guard reconnaissance aircraft was tracked circling over the protests in Washington, D.C.

Air National Guard spokesperson Lt. Col. Devin Robinson subsequently told Air Force Magazine that the aircraft belonged to the West Virginia Air National Guard and was "responding to a District of Columbia National Guard request to provide airborne situational awareness of key lines of communication and critical infrastructure within the District."

Last week, Secretary of Defense Mark Esper ordered a review of the National Guard's controversial response to the demonstrations.

ABC News' Luis Martinez and Ben Siegel contributed to this report.