President-elect Joe Biden says his transition team has been briefed on the massive cyber intrusions recently identified by the U.S. government.
"There's a lot we don't yet know, but what we do know is a matter of great concern," Biden said in a statement on Thursday. "I have instructed my team to learn as much as we can about this breach, and Vice President-elect [Kamala] Harris and I are grateful to the career public servants who have briefed our team on their findings, and who are working around-the-clock to respond to this attack."
The full scope of the attack, which apparently took place over several months, is still unknown. The Department of Homeland Security and the Pentagon are among the entities affected.
Cybersecurity experts say the style of attack points to Russia's foreign intelligence service, but the Trump administration has not publicly made that accusation, and President Trump has not made a statement on the breach.
Biden vowed to make cybersecurity "a top priority at every level of government — and we will make dealing with this breach a top priority from the moment we take office."
Biden's statement came after the Cybersecurity and Infrastructure Security Agency, or CISA, issued a statement saying the breach "poses a grave risk to the Federal Government and state, local, tribal, and territorial governments as well as critical infrastructure entities and other private sector organizations."
CISA says that the breach began in at least March and that the hackers have "demonstrated patience, operational security, and complex tradecraft in these intrusions."
The chairs of the House Oversight and Homeland Security committees and several related subcommittees sent a letter to the Director of National Intelligence John Ratcliffe, FBI Director Christopher Wray and acting Homeland Security Secretary Chad Wolf calling for a classified, interagency briefing on Friday.
The committees also asked the agencies to "provide any damage assessments of the attack, including interim analyses, as soon as practicable."