Washington: Joe Biden's chief of staff on Sunday suggested that the US president-elect, once in office, would take a much stronger line against Russia for its suspected cyberespionage operations, saying the US response would go beyond sanctions.

"Those who are responsible are going to face consequences for it," Ron Klain told US network CBS. "It's not just sanctions. It's also steps and things we could do to degrade the capacity of foreign actors to repeat this sort of attack or, worse still, engage in even more dangerous attacks."

The Biden administration was considering multiple options to punish the Kremlin over its alleged role in the massive cyberattacks uncovered last week that have targeted half a dozen US government agencies. Among them are financial penalties and retaliatory hacks on Russian infrastructure, according to Reuters news agency.

The Kremlin has denied any role in the hacking.

What were the attacks?
The attackers infiltrated over 40 federal agencies, including the departments of Treasury, Energy and Commerce, as well as government contractors.

Officials and cybersecurity professionals across the US are still struggling to determine the scale of the hacking campaign, which managed to breach computer networks using enterprise management network software made by the Texas-based IT company SolarWinds.

The hackers used the software as a springboard to infect clients which included US federal departments.

The cyberattack also hit targets worldwide with the list of victims still emerging, according to researchers.

Trump downplays hacks
Kevin Mandia, the head of cybersecurity firm FireEye, which was targeted by hackers earlier this month, suggested that more cyberattacks were likely to follow and there was little time to spare before the next one.

"These attacks will continue to escalate, and get worse if we do nothing," said Mandia.

US Secretary of State Mike Pompeo on Friday said it was "pretty clear" that Russia was behind the hacking campaign.

However, President Donald Trump has played down the cyberattacks and cast doubt on his administration's assessment. He suggested, without evidence, that China, instead of Russia, could be behind the hacks.

"The Cyber Hack is far greater in the Fake News Media than in actuality," Trump tweeted on Saturday. "Russia, Russia, Russia is the priority chant when anything happens because Lamestream is, for mostly financial reasons, petrified of discussing the possibility that it may be China (it may!)"

US lawmakers demand 'strong response'
Both Republican and Democratic lawmakers have called for a muscular response to the cyberattacks.

Senator Mitt Romney, a frequent critic of Trump, said the data breach was "extraordinarily dangerous," adding that it will "have to be met with a very strong response."

The Republican said that while he was "disappointed" with Trump's comment on Saturday, he expected it. "The president has a blind spot when it comes to Russia," Romney told CNN.

Mark Warner, the top Democrat on the Senate Intelligence Committee, said that the hack could still be going on and that officials had yet to determine its full scope.

"This is in that gray area between espionage and an attack," Warner said on ABC.

He backed Romney's call for retaliation, saying Washington needed to make clear to adversaries "that if you take this kind of action we and others will strike back."