WASHINGTON — Acting Defense Secretary Patrick Shanahan has appointed a four-star officer to take another look at the military’s investigation into the 2017 attack in Niger that killed four U.S. soldiers, and review whether additional punishments should be meted out.

In a statement Thursday, the Pentagon said the investigating officer will do a “new, narrowly-scoped review” and give Shanahan recommendations on whether the reprimands already made were appropriate. The officer’s name was not released.

Officials have said that nine individuals have been held accountable for lapses in training and other mission preparedness. The punishments have largely been letters of reprimand. But officials and members of Congress have questioned whether more senior officers should be disciplined. Officials spoke on condition of anonymity to discuss personnel actions.

Report: Green Beret’s reprimand rescinded after Mattis pushes DoD to revisit punishments for Niger ambush Defense Secretary Jim Mattis was reportedly livid over the possibility that a junior officer who survived the 2017 Nniger ambush would face punishment, while senior leaders would escape blame.

The initial investigation found multiple failures leading up to the October 2017 attack, but determined that none of those shortfalls directly caused the overwhelming enemy ambush and firefight, which also killed four Nigerien troops, wounded a number of forces from both countries, and sent troops running for their lives.

That investigation report came out last May, detailing a series of “individual, organizational, and institutional failures and deficiencies that contributed to the tragic events.” But it concluded that “no single failure or deficiency was the sole reason” for what happened.

It said the U.S. forces didn't have time to train together before they deployed, and did not do preparatory battle drills with their Nigerien partners. And the report said lax communication and poor attention to details led to a "general lack of situational awareness and command oversight at every echelon."

Since then, administrative actions — mainly the letters of reprimand — were taken against nine individuals, including Maj. Gen. Marcus Hicks, who was serving as the commander of special operations forces in Africa at the time. He was the most senior officer punished, leading some to question whether other more senior leaders had unfairly escaped unscathed.

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In addition, a number of troops, including those killed, have been recommended for valor awards, mainly Silver Stars and Bronze Stars. But none of those have been announced, either.

In this Thursday, May 24, 2018, photo, soldiers salute as taps play at the U.S. Army Special Operations Command Fallen Special Operations Soldier Memorial ceremony on Fort Bragg, N.C. The names of four Special Forces soldiers killed last year in an ambush in Niger are among those that have been added to the memorial wall at Fort Bragg. (Andrew Craft /The Fayetteville Observer via AP)

During a House Armed Services Committee hearing last week, Rep. Ruben Gallego, D-Ariz., peppered Shanahan with questions about the lengthy delay in any announcements and when final decisions would be made.

Shanahan said he was aware that his predecessor, Jim Mattis, had received final recommendations and had been reviewing them. But, Shanahan said, "I did not find that sufficient. So, I convened my own review so I can insure from top to bottom as the appropriate accountability."

Gallego said he wanted to be sure the Pentagon review didn't simply place all the blame on junior officers and let senior officers "off the hook."

"These families and the American public deserve to know exactly what happened, and the junior officers that are being reprimanded right now should know that there's going to be equal reprimands, especially for general officers, should they have done anything wrong," said Gallego.

Shanahan responded that the fundamental reason he is doing his own review is to be certain there is a full accounting, from the troops on the ground to the most senior officer.

The U.S. military in Africa has taken a number steps to increase the security of troops on the ground, adding armed drones and armored vehicles and taking a harder look at when American forces go out with local troops. Gen. Thomas D. Waldhauser, head of U.S. Africa Command, has said that the U.S. has cut the response time needed for medical evacuations.

U.S. Special Operations Command has made changes in pre-deployment and readiness training, and addressed other staffing and decision-making shortfalls. The changes include insuring that forces conduct training together before they deploy and the exercises must be evaluated by a senior officer.

The review found that a large personnel turnover after training but before deployment led to some of the problems with the team in Niger.