January 8, 2021

Pelosi, calling Trump 'an unstable president,' seeks to prevent his access to nuclear launch codes

WATCH: Pelosi, Schumer call for 25th Amendment to be used against Trump

In an extraordinary move, House Speaker Nancy Pelosi said Friday she had reached out to the Chairman of the Joint Chiefs of Staff Mark Milley to discuss "available precautions" for preventing what she called "an unstable president" from accessing the nuclear launch codes or initiating military hostilities before he is out of office in 12 days.

She revealed the startling development in a letter to Democratic colleagues Friday morning, a day after she called on Vice President Mike Pence to immediately remove Trump from office by invoking the 25th Amendment and threatening a second impeachment of Trump if Pence failed to act.

Oliver Contreras/Sipa USA via AP
Speaker of the House Nancy Pelosi walks with CBS's 60 Minutes, Lesley Stahl, at the Capitol Rotunda of the US Capitol building during an interview on Jan. 8, 2021, in Washington, DC.

"This morning, I spoke to the Chairman of the Joint Chiefs of Staff Mark Milley to discuss available precautions for preventing an unstable president from initiating military hostilities or accessing the launch codes and ordering a nuclear strike," she said in the letter. "The situation of this unhinged President could not be more dangerous, and we must do everything that we can to protect the American people from his unbalanced assault on our country and our democracy."

White House via Twitter
President Donald Trump addresses the nation from the White House, Jan. 6, 2021, in Washington, DC.

In a terse statement, Col. Dave Butler, a spokesperson for Chairman of the Joint Chiefs of Staff, confirmed the call.

Alex Brandon/AP, FILE
In this Sept. 22, 2020, file photo, Joint Chiefs Chairman Gen. Mark Milley listens before a meeting with Secretary of Defense Mark Esper and Israeli Defense Minister Benny Gantz, at the Pentagon in Washington.

"Speaker Pelosi initiated a call with the Chairman. He answered her questions regarding the process of nuclear command authority."

Olivier Douliery/CNP via Newscom, FILE
In this April 22, 2018, file photo, a US Marine carries the nuclear codes to the White House in Washington, DC.

The White House did not immediately respond to a request for comment.

ABC News' Matthew Seyler contributed to this report.