White House says some employees were fired by mistake

The Department of Energy has paused the firings of hundreds of employees who work for a key agency maintaining the U.S. nuclear weapons stockpile, multiple sources tell ABC News.

Managers with the National Nuclear Security Administration (NNSA) are frantically calling employees back and telling them that -- as of right now -- they're not fired, despite some receiving termination emails and phone calls on Thursday. Their badges are getting turned back on and access to federal systems is being restored, at least temporarily.

Hundreds of probationary employees were terminated Thursday night in the mass Trump administration layoffs. The move prompted concerns of a national security risk because the agency is responsible for maintaining U.S. nuclear weapons, transporting them, and nuclear counterterrorism, among other missions.

NNSA held an all-staff meeting Friday morning, announcing the DOE had agreed to pause the layoffs, due to the agency's national security mission.

NNSA staff tell ABC News they are in a holding pattern. They're still bracing for firings, but possibly not as widespread.

-ABC News' Jay O'Brien

Vice President JD Vance and Ukraine President Volodymyr Zelenskyy met on Friday on the sidelines of the Munich Security Conference.

Both men characterized the meeting as the starting point for negotiations to end the war in Ukraine that began with Russia's full-scale invasion nearly three years ago. Zelenskyy said the conversation was "good" and said they want to achieve peace but that Ukraine requires "real security guarantees."

Hundreds of staff at the agency responsible for maintaining the U.S. nuclear stockpile were fired Thursday in the wave of mass Trump administration terminations, multiple current and former employees told ABC News.

The National Nuclear Security Administration ensures "the United States maintains a safe, secure, and reliable nuclear stockpile," according to its website. The agency also has a team of first responders that deploy to nuclear disasters around the globe and a counterterrorism division, which hunts down nuclear devices in the hands of U.S adversaries.

All of those key functions were impacted by the firings, ABC News' Jay O'Brien was told.

Multiple current and former employees described the situation as "a national security crisis."

Two former staffers confirmed probationary employees began receiving termination notices late Thursday and worried the agency of only about 1,800 employees was losing the key nuclear arms expertise that cannot be replaced.

-ABC News' Jay O'Brien

The Treasury Department's Office of Inspector General and the Government Accountability Office confirmed it will investigate reported access to the Treasury's vast payment systems by DOGE employees.

The Treasury's deputy inspector general wrote in a letter to lawmakers that she initiated an audit on Feb. 6 and they "expect to begin our fieldwork immediately."

"Given the breadth of this effort, the audit will likely not be completed until August; however, we recognize the danger that improper access or inadequate controls can pose to the integrity of sensitive payment systems. As such, if critical issues come to light before that time, we will issue interim updates and reports," the deputy inspector general added.

The letter came after Democratic senators last week raised concerns about DOGE's access to Treasury data.

-ABC News' Allison Pecorin