Anonymous, the loose collective of online hackers, issued an ominous warning to President-elect Donald Trump ahead of his inauguration, telling the billionaire he’s going to “regret” the next four years.

On Twitter, the group put out a call to action to its followers, urging them to expose any potential compromising information they can find about the soon-to-be new leader of the free world.

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The group tweeted at Trump, repeating unsubstantiated allegations that he has “financial and personal ties with Russian mobsters, child traffickers, and money launderers.”

“This isn’t the 80’s any longer, information doesn’t vanish, it is all out there. You are going to regret the next 4 years. @realDonaldTrump,” reads a tweet from @YourAnonCentral, an account used to disseminate information among the hacker group.

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