President Donald Trump said in a tweet Sunday that "they are laughing their asses off in Moscow" at the chaos in the U.S. over Russia's meddling in the 2016 election and the subsequent investigation.

Trump, who has constantly denied his campaign colluded with the Kremlin to interfere in the 2016 election, sent out a series of tweets on Saturday and Sunday about the investigation by special counsel Robert Mueller. Trump has derided it as a "witch hunt" and an excuse for Hillary Clinton's loss to him.

"If it was the GOAL of Russia to create discord, disruption and chaos within the U.S. then, with all of the Committee Hearings, Investigations and Party hatred, they have succeeded beyond their wildest dreams. They are laughing their asses off in Moscow. Get smart America!" he wrote.

The Justice Department announced Friday that Mueller had indicted 13 Russians for their various roles in meddling in the U.S. election through "information warfare" in the form of fraud, identity theft, social media skullduggery and more.

Both Trump and his critics claimed vindication over the indictments, which mentioned the interference campaign began in 2014—before Trump announced his run for president—and also did not state any Americans knowingly assisted in their efforts.

If it was the GOAL of Russia to create discord, disruption and chaos within the U.S. then, with all of the Committee Hearings, Investigations and Party hatred, they have succeeded beyond their wildest dreams. They are laughing their asses off in Moscow. Get smart America! — Donald J. Trump (@realDonaldTrump) February 18, 2018

Opponents said it showed Trump's "hoax" charge about Russia's interference was now bunk, but Trump said he "never said Russia did not meddle in the election," saying his "hoax" charge over the past year was about the notion of collusion. However, he had downplayed it, saying last year he felt Russia meddled but "we also get hacked by other countries."

Trump also tied last week's school shooting in Florida to the Russia probe, slamming the FBI for not following through on a tip about the perpetrator a month before he carried out the massacre.

"Very sad that the FBI missed all of the many signals sent out by the Florida school shooter. This is not acceptable. They are spending too much time trying to prove Russian collusion with the Trump campaign – there is no collusion. Get back to the basics and make us all proud!" Trump wrote.

Very sad that the FBI missed all of the many signals sent out by the Florida school shooter. This is not acceptable. They are spending too much time trying to prove Russian collusion with the Trump campaign – there is no collusion. Get back to the basics and make us all proud! — Donald J. Trump (@realDonaldTrump) February 18, 2018