The Justice Department announced charges Wednesday against 11 people accused of orchestrating a decadelong marriage fraud operation that allegedly engineered more than 1,000 sham marriages between Chinese nationals and U.S. citizens to secure fraudulent green cards.

In his first press conference since he was sworn in this week, Attorney General Todd Blanche called the case “one of the largest marriage fraud prosecutions in United States history,” alleging the operation was a yearslong, multimillion-dollar enterprise designed to help people obtain lawful permanent resident status through fraudulent marriages.