Biden says the Pentagon isn't briefing his team on the suspected Russian cyberattack

President-elect Joe Biden said Tuesday the Pentagon was not briefing his team on pressing matters like the suspected Russian hack of federal government departments and agencies.

Though senior members of the Trump administration say the hack that has hit a number of government departments and agencies looks like Russia's work, President Donald Trump has avoided pointing fingers at Moscow.

Biden, who said the cyberattack fit Russia's pattern of malign behavior, said that when he was sure who was responsible and clear on the extent of the damage, "there will be a response."

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President-elect Joe Biden said Tuesday that the Pentagon was not briefing his team on many issues, including the suspected Russian cyberattack on the US government.

"It is a grave risk, and it continues. I've seen no evidence that it is under control," Biden said in Wilmington, Delaware, of the sweeping cyberattack that has affected a number of federal government departments and agencies.

"The Department of Defense won't even brief us on many things," he added, suggesting that limited cooperation from the Pentagon was hindering his understanding of the situation he would take charge of in just 29 days.

It was revealed earlier this month that hackers compromised systems provided by SolarWinds, a software company whose customers include many US government offices. Through those compromised systems, hackers were able to breach networks across the government and had a monthslong head start to cover their tracks.

The severe hack has affected the departments of Treasury, Commerce, Defense, State, and Energy, according to various reports.

The Cybersecurity and Infrastructure Security Agency characterized the hack as "sophisticated" and said removing the "threat actor" from the compromised systems would be a challenge.

President Donald Trump has avoided pointing fingers at Moscow and insisted that "everything is well under control," but both Secretary of State Mike Pompeo and outgoing Attorney General William Barr have said that Russia appears to be behind the cyberattack.

Ryan Goodman, a former Pentagon legal advisor, tweeted Tuesday that not briefing the incoming administration on this threat "compromises US national security" and was likely a "violation of at least the spirit of the Presidential Transition Act."

Biden's comments on a lack of Department of Defense briefings on critical issues came after his transition team raised concerns Friday about a decision by the Pentagon to delay transition meetings.

As the Department of Defense claimed there was a mutual agreement that the two sides would take a break from the meetings, a spokesperson for Biden's transition team said there was no such agreement and that his side was "concerned" by the "abrupt halt" in cooperation.

The spokesperson, Yohannes Abraham, also said the transition team had run into "resistance" from political appointees at the Pentagon. The Trump administration recently purged the department's leadership and packed the vacant posts with loyalists.

As he spoke Tuesday, Biden criticized Trump's response to the hack, saying that "this president hasn't even identified who is responsible." He said the hack occurred while the president was not paying attention.

"When I learn the extent of the damage and, in fact, who is responsible, they can be assured that we will respond," the president-elect, who said the attack was consistent with Russia's usual pattern of behavior, added. "There are many options, which I will not discuss now. ... I promise you, there will be a response."

"Even if he does not take it seriously, I will," he said.

In response to Biden's remarks, a Pentagon spokesman told Insider that Biden's transition team "should contact the Cyber Unified Coordination Group (UCG) for a brief on this topic."

Acting Secretary of Defense Chris Miller said Friday that the department had been cooperating with the transition team.

He said in a statement that the Pentagon would fulfill its departmental transition obligations because "this is what our nation expects," adding that "DoD will deliver AS IT ALWAYS HAS."