Hackers believed to be working for the Russian government violated the Democratic National Committee's network, and spied internal communication by capturing data from Democratic presidential candidate Donald Trump.
Two separate groups reportedly have entered the DNC system, managing to read all emails and watch chat communications for almost a whole year before being identified, according to CrowdStrike Security Company, which has undertaken to correct security gaps.
Russian spies also watched the networks of presidential candidate Hillary Clinton, as well as the computers of some Republican political action committees, according to a Washington Post publication.
A spokesman for the Russian government denied all involvement in the violations.
"We completely rule out the possibility that (Russian) government or state bodies may have been involved," Dmitry Peskov, a Kremlin spokesman, told Reuters in Moscow.
The invasion is indicative of the complexity of the technique of Russian hackers, which intelligence officials have long considered them to be the most talented ones.
The Democratic Party was reportedly aware of the hackers' attempts to eavesdrop material of Trump for two months, and the US Secret Service had even been involved in trying to find out who was behind the hacking, said a source familiar with the opposition investigation.
The same source reported that agents of the Democratic Party believed that the hack was carried out by the Russian government.
The online ones attacks against political candidates and organizations are common throughout the world. The Director of the National Intelligence Service (NSA) James Clapper said last month that he was aware of campaign hacking attempts and that he expected more to be discovered by the Nov. 8 presidential election.
The first group that according to CrowdStrike is named Cozy Bear broke into the DNC's systems last summer. It mainly monitored emails and chat conversations, and the hackers may be working for Russia's Federal Security Service, or FSB.
The second group was called Fancy Bear, and they are likely to work for account of the military of Russia. The team was able to gain access in late April and "went straight to OPPO's research ... on Donald Trump."
It should be noted that in the last two US presidential cycles in 2008 and 2012 there was a draw attacks in cyberspace by many adversaries that targeted the campaign of President Barack Obama and the campaigns of his Republican opponents.
US intelligence officials have reported that many previous attacks have been linked to Chinese hackers.