Sen. John McCain lashed out Thursday at protesters who loudly interrupted a hearing with former Secretary of State Henry Kissinger, calling their demonstration "disgraceful" and the protesters "low-life scum." 

The incident also raised immediate questions about how the demonstrators could get within inches of Kissinger with no apparent interference.

US Capitol Police spokeswoman  Kim Schneider said later the force did not "meet the standards expected of the USCP" during the disruption.

The protest broke out at the opening of a Senate Armed Services Committee hearing on national security and global challenges, where Kissinger and other prominent former secretaries of state were testifying. Standing inches behind the Nixon-era diplomat, the protesters shouted, "Arrest Henry Kissinger for war crimes." 

The disruption lasted about two minutes. As officers led the protesters away, McCain, R-Ariz., who chairs the committee, apologized to Kissinger. 

"I have never seen anything as disgraceful and outrageous and despicable as the last demonstration that just took place," he said. 

McCain then threatened to have the demonstrators arrested. After another outburst, the senator responded: "Get out of here, you low-life scum." 

As they were escorted out of the room, others in the hearing room applauded. 

Kissinger remains a controversial figure. The protesters referenced the secret U.S. bombing campaign in Cambodia during the Vietnam War, and other Nixon-era actions he was involved in. 

McCain, who served in Vietnam, has a personal connection to Kissinger and brought it up shortly after the protesters left. While McCain was imprisoned in Hanoi during the Vietnam War, Kissinger is said to have refused an offer to bring McCain home with him during final talks to end the war. As McCain tells it, Kissinger said he would be brought home in the same order as the other prisoners, knowing that to do otherwise would imply favoritism (McCain's father was a four-star admiral in the Navy). 

During Thursday's hearing, McCain thanked Kissinger for saving his honor.