President Trump on Friday targeted Representative Ilhan Omar for remarks she made during a speech on civil rights and Muslims in America with a graphic video featuring the burning World Trade Center towers and other images from Sept. 11, 2001, that he tweeted to millions of his followers.

The Twitter post from the president stoked and amplified a controversy that has been a focus of conservative news outlets, which have sought to elevate Ms. Omar — a Minnesota Democrat and one of the first Muslim women elected to Congress — as a political target, as Mr. Trump’s re-election campaign begins in earnest.

At issue were remarks that Ms. Omar made last month at an event hosted by the Council on American-Islamic Relations. There, she gave a speech in which she addressed lingering fear directed at Muslims, and the rights Muslims have to speak out about being viewed with suspicion.

During the speech, she said that Muslims had “lived with the discomfort of being a second-class citizen and, frankly, I’m tired of it, and every single Muslim in this country should be tired of it.” She added that the council was created after the Sept. 11 attacks “because they recognized that some people did something and that all of us were starting to lose access to our civil liberties.” (The Council on American-Islamic Relations was actually founded in 1994.)