A Super PAC called Americans United for Values has posted 25 billboards around Cincinnati, Ohio, to draw attention to the 2012 Benghazi terrorist attack and Hillary Clinton's response to it as secretary of state.
They are on the city's main highways as well as other roads around the city.
"It is unconscionable that our nation's leaders stood idly by as Americans came under attack," said AUV treasurer Brian Kinnett in a statement. "Those in Washington who failed our service men and women have not been held accountable, and we will continue to fight for justice for the Benghazi Four. We believe this is what this election should be about."
The Benghazi attack on the diplomatic compound left four Americans dead, including U.S. Ambassador Chris Stevens, and Clinton's handling of the consulate's security and the attack's aftermath has drawn criticism from Republicans ever since.
Among the criticisms Clinton has received was initially saying the attack was the result of a protest against an anti-Islamic video, despite emails the night of the attack showing Clinton knew the attack had "nothing to do" with the film.
In 2013, while testifying about the attack before Senate Foreign Relations Committee, Clinton infamously remarked, "With all due respect, the fact is we had four dead Americans. Was it because of a protest, or was it because of guys out for a walk one night who decided they'd go kill some Americans?"