FBI Director James Comey says that Russia is the "greatest threat of any nation on Earth, given their intent and capability."
Mr Comey made the comments during a Senate hearing in which he discussed the ongoing investigation into Russian influence on the 2016 US election. The top FBI official told senators that Russians have been meddling in American politics and that they have continued to do so recently.
"One of the biggest lessons learned is that Russia will do this again. Because of 2016 election, they know it worked," Mr Comey said of the threat that Russia might try to influence future elections.
Mr Comey first acknowledge that the FBI had opened an investigation into Russian meddling in the presidential election in March when he testified before the House Intelligence Committee. The intelligence agency is working to determine whether any associates of President Donald Trump were involved in the Russian efforts to sway the election, he said then. Democrats gleaned some satisfaction from the revelation but were critical that Mr Comey had not revealed that investigation sooner.
The Trump administration has been plagued by suspicions that associates of the campaign and the allegations have already led to some significant scandal for the president.
Less than a month after Mr Trump was sworn into office, National Security Adviser Michael Flynn was forced to resign from his position serving the White House after it was discovered he had lied to Vice President Mike Pence about the substance of a phone call he had had with Russian ambassador to the US Sergey Kislyev during the transition period following the election. Mr Flynn had failed to tell Mr Pence that he had discussed Russian sanctions that were established by former President Barack Obama after US intelligence agencies determined that Russia had interfered in the US election campaign.
Before the Senate hearing Mr Trump sent out a series of tweets criticising the investigation into potential collusion between his campaign and Russia. In those tweets, Mr Trump charged that Mr Comey was the best thing to happen to his 2016 Democratic opponent Hillary Clinton because the FBI director had found that her use of a private email address while serving as secretary of State was not breaking the law.
"Trump/Russia story was an excuse used by the Democrats as justification for losing the election. Perhaps Trump just ran a great campaign?" Mr Trump tweeted.