(Still from video.)

A man was removed from the crowd during a speech by Sarah Palin at Wednesday's anti-Iran deal protest on the west side of the U.S. Capitol. The man, who appeared to be African American, was escorted out by several uniformed officers shortly after Palin enthusiastically praised police officers.

"Since our president won't say it," Palin said, "since he still hasn't called off the dogs, we'll say it: Police officers and first-responders all across this great land, we got your back! We salute you!"

She pointed around the crowd, adding to cheers, "Thank you, police officers!"

Former Alaska governor Sarah Palin criticized President Obama's treatment of police officers during a rally at the Capitol against the Iran nuclear deal. (AP)

The "called off the dogs" remark, while employing a common expression, was quickly interpreted to be a reference to protests and protesters from the Black Lives Matter movement, which seeks fairer treatment of African Americans by police and highlights the inordinate number of blacks killed by law enforcement.

Shortly after her comment, there was a disturbance in the crowd, noticeable in C-SPAN's televised broadcast of the event. Palin continued her speech, talking about Obama negotiating with "the braggadocious No. 1 state sponsor of terrorism" -- Iran -- and then trailing off as a shouting voice could be heard in the crowd. Appearing to be interacting with the person, Palin uttered a curt "good" as a bodyguard appeared over her shoulder.

At that point, the man was forcibly removed from the audience. As he was escorted out, he appeared to be arguing with the officers around him.

During a speech at the U.S. Capitol opposing the international nuclear deal with Iran, Sarah Palin was interrupted by a protester who had to be escorted out by police. (AP)

It's not clear if the man who was removed from the event was responding to Palin's reference to police officers. Republican candidates for president have regularly dismissed the Black Lives Matter movement, including Donald Trump, who on Tuesday night told Fox News Channel's Bill O'Reilly that members of the movement were "trouble."

Palin continued her speech without further incident. Hers was one of dozens during the event organized by the conservative Tea Party Patriots, meant to apply belated pressure on Congress to reject the deal. It already has enough support from Democrats to ensure approval.