Critics say the objectives of the Iran war are ill defined, the justification is frequently shifting, the timeline is open-ended: It is the kind of conflict Hegseth fought in -- and denounced -- but is now defending.

"America is winning -- decisively, devastatingly and without mercy," Hegseth said Wednesday. "We have only just begun to hunt, dismantle, demoralize, destroy and defeat their capabilities."

"To the media outlets and political left screaming endless wars: Stop. This is not Iraq. This is not endless," he said two days earlier. "Our generation knows better, and so does this president."

The war is the fifth major international US military intervention under Hegseth, following strikes on Yemeni rebels, an operation targeting Iranian nuclear sites, attacks on alleged drug-smuggling boats, and a raid to seize Venezuelan leader Nicolas Maduro.

While US personnel were wounded in the Maduro raid, the operations Hegseth has overseen have been largely bloodless on the American side, until now: Six US troops have been killed so far during the Iran war.

Hegseth, a 45-year-old former Fox News co-host, criticized the media this week for highlighting negative developments in the war, claiming that "the fake news misses" the overall picture of US success.

"We've taken control of Iran's airspace and waterways without boots on the ground... But when a few drones get through, or tragic things happen, it's front-page news," Hegseth said, accusing the media of wanting "to make the president look bad."

- 'Peace is our goal' -

A decorated infantry officer who spent more than 18 years in the National Guard and served in combat, deploying to Iraq and Afghanistan, Hegseth has nonetheless been been plagued by scandals.

He came under fire during his confirmation process over alleged financial mismanagement at veterans' nonprofits where he previously worked, as well as reports of excessive drinking and allegations of sexually assaulting a woman in California.

A few months after he took office as defense secretary, Hegseth was hit by a scandal related to the strikes on Yemen.

The Atlantic magazine revealed that its editor in chief had been inadvertently included in a Signal chat in which Hegseth and other officials discussed the imminent operation, with the Pentagon chief sending messages on the timing of strikes hours before they happened.

Another controversy stemmed from a September 2 attack on an alleged drug-smuggling boat. After the initial strike left survivors, a follow-up strike killed two of them -- what one lawmaker said amounted to an attack on "shipwrecked sailors."

In another contentious move under Hegseth, a number of senior military personnel, including the top-ranking general Charles "CQ" Brown, have been fired, often with little or no public explanation.

Hegseth said in a December speech that the Pentagon "will not be distracted by democracy-building interventionism, undefined wars, regime change, climate change, woke moralizing and feckless nation building."

"We will deter war. We will advance our interests. We will defend our people. Peace is our goal," he told the Reagan National Defense Forum.

Less than three months later, the United States was at war with Iran, a conflict that has since expanded to other countries in the Middle East.

"For 47 long years, the expansionist and Islamist regime in Tehran has waged a savage, one-sided war against America," Hegseth said this week.

"We didn't start this war," he said. "But under President Trump, we are finishing it."