As President Donald Trump pressed the National Guard and Marines’ deployment to U.S. cities, military leaders privately questioned the troops’ training and cautioned about the “far-reaching social, political and operational” risks of supporting law enforcement, according to military records reviewed by Reuters and disclosed in court.

U.S. Army officials planning an operation in MacArthur Park during the June deployment in Los Angeles determined that using troops to protect agents carrying out Trump’s immigration crackdown posed an “extremely high” risk to civilians, troops and the military’s reputation, according to an internal document.

Officials warned that the operation could attract protests and spiral into a riot with potential for “miscommunication and fratricide” as well as accidental harm to civilians, including children, the operation planning document said.

The trove of internal military reports and messages, disclosed during a trial to resolve a lawsuit by California Governor Gavin Newsom, offers a rare inside look at concerns from commanders after Trump broke a long-standing tradition against using the military in support of domestic law enforcement over the objections of local officials.

Since deploying 4,000 National Guard and 700 U.S. Marines to Los Angeles to quell protests against immigration arrests, Republican Trump has sent National Guard troops to Washington and is considering expanding the military presence in other Democratic-run cities.

To mitigate the risks of the Los Angeles deployment, military lawyers drafted rules for using force and de-escalation that troops could access on their phones and that warned of the high stakes of the deployment.

“The very nature of domestic operations — American military forces operating in U.S. communities — has such significant implications that the mistakes of a few soldiers can have far-reaching social, political, and operational effects,” according to an undated document titled “Los Angeles Civil Unrest SRUF.” The acronym means Standing Rules for the Use of Force.

Louis Caldera, Army Secretary to Democratic former President Bill Clinton, said in an interview that deploying the military domestically threatens to put soldiers and civilians at risk, undermines recruitment and erodes public support.

“Trump has broken a lot of norms,” said Caldera. “His predecessors would not use the military in this way.”

The Department of Defence declined to comment on a subject of ongoing litigation.

‘Not A Loaded Question’

While state governors often deploy National Guard troops under their command to help during disasters such as hurricanes, in Los Angeles, they were called into federal service by the president.

Newsom has alleged that they have been engaged in law enforcement, in violation of an 1878 law known as the Posse Comitatus Act. The Trump administration argued the troops are not enforcing the law, but have been used solely to protect federal buildings and personnel, including immigration agents.

A ruling in the case could come any day from U.S. District Judge Charles Breyer in San Francisco.

A spokesperson for Newsom said the evidence in the trial showed the deployment was “pure political theatre” and a “display of power meant to intimidate our communities.” Only a few hundred troops remain.

After ordering troops to Los Angeles, Trump said his administration would “liberate” the city. Meanwhile, Army leaders were questioning whether three hours of “civil disturbance training” was sufficient, according to internal messages.

“In your experience, does this training provide a suitable level of risk mitigation for the current conditions in Los Angeles? This is not a loaded question,” a U.S. Army officer wrote to fellow officers, whose identities were redacted, one day after Trump ordered the National Guard to Los Angeles. No response messages were disclosed in the court filings.

A week later, the Department of Homeland Security requested military assistance with an operation in MacArthur Park, a gathering spot for immigrants where federal agents believed there was an open-air market for fake identification.

At the trial, Army Major General Scott Sherman testified that he rejected the request because he believed there was little need for military protection. Sherman said he was overruled by Secretary of Defence Pete Hegseth, and the park operation eventually took place on July 7.

The operation was “extremely high” risk with the addition of troops, according to a July 1 Army planning document that was disclosed in the court record. It created the potential for violent protests with the possibility for “miscommunication and fratricide” as well as accidental harm to civilians, including children. A planning map marked the locations of several nearby schools.

Laura Dickinson, a professor who specialises in national security at The George Washington University Law School, said the deployment came loaded with risk for troops.

“Placing them in these highly risky situations puts them on a knife’s edge — and potentially damages the U.S. military’s reputation and broad support across the U.S. population,” she said.

Military planners aimed to mitigate these risks with dress rehearsals at a base in Los Alamitos, California, and training on rules of force, according to the July 1 planning document.

In the end, the MacArthur Park operation lasted around an hour and appeared to take place without incident, according to a report by the Associated Press. Reuters could not independently verify the account. The city’s mayor, Democrat Karen Bass, called the operation a “political stunt.”

The Department of Homeland Security did not respond directly to questions about the operation in MacArthur Park or whether it had resulted in arrests, but said its Immigration and Customs Enforcement and Border Patrol agents had arrested more than 5,000 people in Los Angeles since June.

Sharing Lessons

While planners were preparing for the park mission, military leaders were already sharing lessons learned in Los Angeles with officers in other regions in anticipation of deployments elsewhere.

One July 1 email chain described military members in uniform in Los Angeles being harassed, protests at hotels where immigration agents were housed, and attempts by protesters to dox, or publicly identify, members of the National Guard.

“This is an evolving situation, but coming soon to a region near (hopefully not as contentious)!” said one message. The identity of the defence coordinating officer who sent it, and the recipients, were redacted.

The documents often refer to rules on the use of force, which every soldier in Los Angeles was expected to know, as a way to mitigate risk.

The rules of force document ends with a “cautionary tale” of Marine Corporal Clemente Banuelos that highlights the stakes. Banuelos was on a joint mission with Border Patrol agents in 1997 in Texas when he killed a teenager who was armed with a rifle. Banuelos was never prosecuted, but the shooting was investigated by three grand juries, according to the document.

The “incident remains a powerful reminder that when military personnel employ force, their actions and decisions and the rules that they follow may be subject to outside scrutiny from many levels,” the document said.

(With inputs from Reuters)