The indictments were announced Friday by Deputy Attorney General Rod Rosenstein as part of the ongoing special counsel probe into potential coordination between the Trump campaign and Russian Federation.
Hillary Clinton's campaign organization and the Democratic National Committee may have been targets, including Clinton campaign chairman John Podesta, but Rosenstein declined to identify them.
All 12 of the defendants were connected to GRU, a Russian Federation intelligence agency within the Russian military. They used a scheme known as "spearfishing" which tricked users into disclosing their information that allowed hackers to gain access to emails. That led to the resignation of then-DNC Chairwoman Debbie Wasserman-Schultz.
CNN's Jake Tapper explained why the bombshell indictments from special counsel Robert Mueller on Friday were such a significant development in the 2016 election interference case, calling it a "remarkable turn of events".
"The conspirators corresponded with several Americans through the internet", Rosenstein explained, adding, however, that, "The is no allegation in this indictment that the Americans knew they were corresponding with Russian intelligence officers".
A few hours before the indictments were announced, Trump described the Mueller investigation as a "rigged witch hunt" that is hurting the USA relationship with Russian Federation. House Republicans have threatened to hold Rosenstein in contempt of Congress for what they say is the Justice Department's failure to comply in a timely manner with a subpoena for documents related to the Clinton email and Trump-Russia investigations.
"Our response must not depend on which side was victimized", Rosenstein said.
US intelligence agencies have concluded that Putin personally ordered a campaign to undermine "public faith in the USA democratic process" with the goal of hurting Clinton's candidacy and ultimately helping to elect Trump.
And the announcement came at the same time that Trump and the first lady were meeting at Windsor Castle with the Queen. Trump told reporters on his visit to the United Kingdom on Friday that he planned to "ask" Putin about Russia's attack on the election.
Trump has gone back and forth as to what he acknowledges about what took place and cited Russia's official denials about its active measures.