The incoming administration of President-elect Joe Biden warned Friday of risks to national security after it said the Pentagon suddenly halted briefings for the transition team.

Yohannes Abraham, executive director for the Biden transition team, said he was "concerned to learn this week about an abrupt halt in the already limited cooperation there."

President Donald Trump, who is refusing to acknowledge his election loss to Biden, until recently held back from allowing government agencies to cooperate with Biden's team, as is the custom.

On Friday, Trump's acting defense secretary, Chris Miller, said in a statement that the two sides had a "mutually agreed upon holiday pause" on briefings with military officials.

Abraham said this was not true.

"There was no mutually agreed upon holiday break," he told reporters, warning that "a failure to work together could have consequences well beyond" Biden's inauguration in January.

The latest stumble in what is traditionally a carefully choreographed handover of power between outgoing and incoming US administrations comes as Washington reels from a massive, possibly Russian state cyber attack.

"There's no time to spare," Abraham said.

Trump has yet to give a direct statement on the hacking breach or to comment on allegations by senior politicians and private cyber security companies that it was carried out by Moscow.

Abraham said the attack was of "great concern" and that under Biden cyber attacks will meet a response inflicting "substantial cost."

According to Abraham, the Biden team has "hope and expectation" that the Pentagon briefings will recommence "immediately."

Pentagon says it's cooperating with transition but Biden team disagrees
Washington DC (UPI) Dec 18, 2020 –

Acting Secretary Christopher Miller on Friday cited the Pentagon's cooperation and involvement in the White House transition process, pointing to participating in numerous interviews and fulfilling scores of information requests.

The Biden team said, however, that it is not getting full cooperation.

"As of today, we have supported 139 interview sessions [of] more than 200 DoD personnel, 161 requests for information, and disclosed thousands of pages of non-public and classified documents, exceeding prior transitions," Miller's statement says in part.

It added: "At no time has the Department cancelled or declined any interview. Our key focus in the next two weeks is supporting essential requests for information on OWS [Operation Warp Speed, the White House anti-pandemic campaign] and COVID-19 information to guarantee a flawless transition."

Miller's statement mentioned a "mutually agreed-to holiday pause," which begins Saturday, but on Friday, Biden spokesperson Yohannes Abraham directly contradicted that claim.

"Let me be clear, there was no mutually agreed-upon holiday break," Abraham said, "That our agency review teams will be able to have access to the sort of information that is invaluable for keeping the homeland safe.

"We think it's important that briefings and other engagements continue during this period as there's no time to spare, and that's particularly true in the aftermath of ascertainment delay" — a reference to the delay by the administration of President Donald Trump in officially recognizing Biden as president-elect.

It also cites the Pentagon's participation with Biden's agency review teams, which are responsible for understanding the operations of each government agency to ensure a smooth transfer of power.