Speaking at his first media briefing since May, Hegseth said that no Secretary of War or Defence had ever been impeached for carrying out lawful military operations in the 250-year history of the American republic.
The impeachment push was initiated by outgoing Republican Congressman Thomas Massie, who has accused Hegseth of actions warranting removal from office over his handling of the US military campaign against Iran.
Hegseth calls impeachment push a political stunt
Taking aim at Massie, Hegseth described the impeachment effort as a politically motivated campaign led by a disgruntled lawmaker who had lost his primary election to a candidate backed by US President Donald Trump.
"It's a political spectacle, a personal manifesto driven by ego and resentment. Time for one man's final days in Congress to try to do damage to this president. It's a farce, and it's a stunt, and everybody knows it," Hegseth said on Tuesday.
The resolution comes amid mounting political fallout over the US war with Iran, which has attracted widespread international criticism and reportedly taken a political toll on Republicans following their crushing defeat in the recent midterm elections.
Defending the military campaign, Hegseth insisted that the conflict should be viewed in its broader historical context.
"History will judge the Iran war quite differently than conventional wisdom right now," he said, adding, "We didn't start this war. Iran did 47 years ago."
'High crimes and misdemeanors': What the resolution says
Although the impeachment resolution primarily focuses on American military operations in Iran, it also raises questions about Hegseth's role in military actions in Yemen against Iranian-backed Houthi rebels and operations in Venezuela.
The resolution alleges that Hegseth's conduct amounts to "high crimes and misdemeanors" and argues that his leadership at the Pentagon warrants impeachment.
However, the US Constitution does not provide an exhaustive definition of what constitutes high crimes and misdemeanors. It is ultimately up to lawmakers to determine whether the alleged conduct meets the threshold for impeachment.
'I would do it again tomorrow': Hegseth defends military operations
Rejecting the allegations, Hegseth stood firmly behind the administration's military actions in Iran, Yemen and Venezuela, as well as operations targeting boats allegedly involved in drug trafficking.
He said he supported every operation carried out under his leadership at the Pentagon and expressed no regret over the decisions.
"I was proud to execute them, and I would do it again tomorrow," he said.
Hegseth also argued that the impeachment effort was effectively an attack on American service members who carried out the missions.
"These resolutions tell every one of them that their service was a crime. Their service was not a crime. These are heroes," he said.
He maintained that targeting the country's military leadership over operational decisions would undermine the morale of American troops and send the wrong message to those serving in uniform.