LinkedIn co-founder Reid Hoffman apologized Wednesday for funding a group linked to the spreading of disinformation in the 2017 Alabama Senate runoff election.

In a blog post, Hoffman, a billionaire who is active in Democratic Party politics, said he was unaware that the group was tied to a project that used tactics that had been used by Russia to interfere with the 2016 U.S. presidential election to discredit Republican candidate Roy Moore.

“ “I categorically disavow the use of misinformation to sway an election.” ” — Reid Hoffman

“I have deliberately funded multiple organizations trying to re-establish civic, truth-focused discourse in the U.S.,” Hoffman wrote. “I would not have knowingly funded a project planning to use such tactics, and would have refused to invest in any organization that I knew might conduct such a project.

“Nevertheless, I do have an apology to make and have learned a lesson here.”

Last week, the New York Times reported that Democratic political operatives used deceptive tactics inspired by Russian Facebook and Twitter efforts as an “experiment” during the tightly contested Alabama race, which was narrowly won by Democrat Doug Jones. The Times reported that the project’s $100,000 in funding had come from Hoffman. Experts told the Times that the disinformation campaign was likely too small to influence the outcome of the election.

Hoffman has reportedly given about $750,000 to the group, American Engagement Technologies, the Washington Post reported.

“To reiterate yet again, I find the tactics that have been recently reported highly disturbing,” Hoffman wrote. “For that reason, I am embarrassed by my failure to track AET — the organization I did support — more diligently as it made its own decisions to perhaps fund projects that I would reject.”