US President Donald Trump (Photo: AFP/VNA)

“I have been fully briefed and everything is well under control,” Mr Trump tweeted on Saturday in his first public comments on the hack, undercutting the assessment that Russia was to blame.

The US government on Wednesday confirmed a recent cyber-attack campaign affected the federal government networks, rating the attack as serious and ongoing.

According to preliminary information, a team of sophisticated hackers won access to internal communications at the US Department of Homeland Security. The breach was part of the campaign that penetrated the US Departments of Treasury and Commerce.

The US government issued an urgent directive asking federal agencies to tighten measures to ensure cybersecurity.