The House of Representatives introduced a resolution to impeach Pete Hesseth.
The initiator was Republican Congressman Thomas Massey. The charges include abuse of power and carrying out an operation against Iran without congressional approval.
Pentagon chief Pete Hegseth said he was "not concerned" by efforts to impeach him.
"Tomorrow morning at the Pentagon we will hold a press conference on this very issue," Hesset said.
In September, Thomas Massey had already raised the issue of impeaching Geseth, but then House Speaker Mike Johnson canceled the last meeting before the midterm elections.