The US has charged seven Iranians for allegedly hacking nearly 50 financial companies and a New York dam.
The attacks, occurring from 2011 to 2013, are believed to have been co-ordinated from Iranian companies.
The US Department of Justice revealed an indictment against the seven Iranians believed to be working for their government.
The indictment calls them “experienced computer hackers” and officials said the attacks were a “wake-up call”.
The attacks “threatened our economic well-being and our ability to compete fairly in the global marketplace – both of which are directly linked to our national security,” said US Attorney General Loretta Lynch.
“And we believe that they were conducted with the sole purpose of undermining the targeted companies and damaging the online operation of America’s free market.”
Mrs Lynch said the attacks cost the victims tens of millions of dollars.
The seven defendants face a maximum sentence of 10 years in prison for conspiracy to commit and aid and abet computer hacking.