The Department of Defense on Saturday announced the formation of a bipartisan commission to determine whether the United States recently fought a war with Iran, with officials saying the panel’s work would help guide future planning regardless of its findings.

The Joint Commission on Recent Hostilities, or JCRH, will be staffed by 14 members drawn from the Pentagon, the State Department, the National Security Council, two former federal judges, and one representative from the American Enterprise Institute. Its mandate, according to a 31-page charter released by the Office of the Secretary of Defense, is to “assess, in a manner consistent with applicable statute and prevailing scholarship, whether the events of March and April 2026 constituted an armed conflict, a series of armed exchanges, or some other category of activity.”

A preliminary determination is expected in the fourth quarter of 2028. A final report will follow within 18 months of the preliminary determination, officials said.

“It is critical that the American people receive a thorough and impartial accounting,” said Deputy Defense Secretary Lawrence Penhall, speaking at a brief news conference at the Pentagon. “Premature conclusions, in either direction, would be unhelpful.”

Mr. Penhall declined to characterize the six-week period in which approximately 380 American service members died, $4.1 billion in munitions were expended and four U.S. carrier strike groups were repositioned to the Persian Gulf. Pressed by reporters, he said the question of whether those events amounted to a war was “exactly the kind of question the commission has been set up to address.”

The announcement was greeted with cautious approval on Capitol Hill, where members of both parties said the commission’s work was overdue.

“For too long, we as a nation have rushed to judgment about whether wars have happened,” said Sen. Margaret Aldrich, R-Ohio, who serves on the Senate Armed Services Committee. “I think a careful, methodologically rigorous review is precisely what this moment requires.”

Sen. David Bream, D-Oregon, said in a statement that he supported the commission but had concerns about its independence. He noted that 11 of the 14 members had served in some capacity during the events under review, and that the commission’s chairman, retired Vice Adm. Robert Glassman, had personally authorized three strikes on Iranian air-defense installations on March 17.

A Pentagon spokeswoman, Capt. Jeanine Voss, said Vice Adm. Glassman’s prior role would not affect the commission’s findings. “Admiral Glassman has agreed to recuse himself from any votes pertaining to strikes that he personally ordered,” Capt. Voss said. “Other votes, he will participate in normally.”

The commission’s budget is set at $48 million over its first two years, with an additional $19 million earmarked for office space at a leased facility in Crystal City, Va. A spokesman for the General Services Administration said the building had previously housed a 2017 commission on lessons learned from the 2003 invasion of Iraq, which delivered its final report in November 2024 and concluded that “additional study is warranted.”

Several outside experts said the new commission represented a useful institutional development.

“We have entered a period in which the line between war and not-war has become genuinely difficult to draw,” said Dr. Helena Marchetti, a senior fellow at the Brookings Institution and the author of three books on the legal architecture of armed conflict. “I welcome any serious effort to think through these questions, even if I disagree with the framing of the question itself.”

Dr. Marchetti added that she had been invited to testify before the commission in early 2027 and had agreed to do so.

The commission’s charter specifies that it will examine, among other matters, the question of whether the ceasefire announced on April 12 and implemented on April 15 should properly be described as a ceasefire, a cessation of hostilities, a pause, or a “mutually agreed deescalation pattern.” The charter notes that each term carries distinct legal implications under U.S. and international law and that the matter has not been authoritatively settled.

It will also consider whether the 380 Americans who died during the period should be classified as combat fatalities, non-combat fatalities, or “service members killed in the course of duties consistent with deployment.” Family members of service members killed during the period will be invited to submit written statements, which the commission has committed to read.

A separate Pentagon working group, established last week, will determine the proper terminology for use in official department communications until the commission delivers its findings. In the interim, internal guidance issued Friday instructed Pentagon staff to refer to the period as “the recent operational environment.”

The White House said President Donald Trump supported the commission’s work and looked forward to its findings.

“The president has been clear that we will get to the bottom of what happened, who is responsible for it happening, and whether it did in fact happen,” press secretary Caroline Lord said. “Those are three separate questions, and the commission will address each in due course.”

Reporters asked Ms. Lord whether the president himself considered the events of March and April to have been a war. She said the president’s position was that the question was one for the commission.

The commission will hold its first organizational meeting on June 3. A public website is expected by late summer, officials said, pending a determination by the Office of Management and Budget on whether it is permissible to publish the commission’s mandate before its mandate has been fully studied.

Additional commissions are under consideration.