Top military leaders have gone public in the past week to disagree with Defense Secretary Jim Mattis on the possible erosion of "unit cohesion" and readiness that Mattis said might come from allowing transgender troops to serve openly in the ranks.

The latest to come forward was Sergeant Major of the Army Dan Dailey.

"We haven't heard" of any problems with unit cohesion since transgender troops were cleared to serve under the Obama administration in 2016, Dailey said at an off-camera session with Pentagon reporters Friday.

In addition, "I have received no formal reports" on dissension in the ranks or morale problems caused by the presence of transgender troops, Dailey said.

Army Secretary Mark Esper, who joined Dailey at the briefing, also said that transgender troops currently serving have not been a problem in terms of unit cohesion or other issues.

Esper then cut short the discussion, citing the ongoing cases in four federal district courts that have indefinitely blocked the Pentagon from acting against transgender individuals currently serving, or barring the recruitment and retention of transgender individuals.

In his memo to President Donald Trump last month effectively supporting a ban on transgender individuals serving in the military, Mattis cited the difficulties of reconciling gender dysphoria with military service.

Gender dysphoria has been defined as the conflict between a person's biological sex and the gender with which that person identifies psychologically and emotionally.

Those with gender dysphoria "could undermine readiness, disrupt unit cohesion, and impose an unreasonable burden on the military that is not conducive to military effectiveness and lethality," Mattis said in the memo that summarized a six-month internal study he ordered.

The study followed several tweets sent out by Trump last summer in which he argued for a ban on transgender military service.

"After consultation with my Generals and military experts, please be advised that the United States Government will not accept or allow [transgender individuals] to serve in any capacity in the U.S. Military," Trump said in a tweet last July.

The Pentagon study backing up Trump included input from the service chiefs, according to Mattis, but those same chiefs have since clearly stated that they've had no problem with transgender individuals in their ranks.

Last Thursday, as Mattis was before the House Armed Services Committee supporting an effective ban, on transgender troops, Army Chief of Staff Gen. Mark Milley was testifying before the Senate Armed Services Committee.

"No, not at all," Milley said when asked by Sen. Kirsten Gillibrand, D-New York, whether transgender troops posed a problem for unit cohesion.

In testimony before SASC on Thursday, Chief of Naval Operations Adm. John Richardson and Gen. Robert Neller, the Marine Commandant, also said they have seen no discipline, readiness or unit cohesion problems arising from having transgender individuals serve openly.

"I am not aware of any issues," Richardson said. He said the Navy applied lessons learned from integrating women sailors into submarines in adapting to transgender sailors. He said that maintaining a "standards-based approach seems to be the key to success."

Neller said he had met with several Marines and sailors who have identified as transgender individuals. "I learned about their desire to serve," he said. "As long as they can meet the standard of what their particular occupation was, I think we'll move forward."

Adm. Paul Zukunft, the Coast Guard Commandant, said the Coast Guard has no problems with allowing transgender individuals to serve openly.

Zukunft told the House Appropriations Homeland Security Subcommittee Wednesday that he has a transgender individual on his personal staff.

"We are certainly committed to their continued service in the United States Coast Guard," he said.

The top leaders' open disagreement with Mattis underlined the potential difficulties he will have in enforcing a ban if the courts permit it.

"The Secretary is in an untenable situation," said Matt Thorn, executive director of the OutServe-SLDN advocacy group. “[Mattis] is in an untenable situation because of the president of the United States.”

Federal District Court judges in Seattle, Washington, D.C., Baltimore and Riverside, California, have all blocked the transgender ban and ordered the military to continue recruiting and retaining transgender individuals.

In the Seattle case (Karnoski v. Trump), Judge Marsha Pechman earlier this week ordered Justice Department and advocacy group lawyers to prepare for trial but gave notice that the government will have a high standard to meet in proving that a ban is constitutional.

"Because transgender people have long been subjected to systemic oppression and forced to live in silence, they are a protected class," Pechman wrote in her ruling. "Therefore, any attempt to exclude them from military service will be looked at with the highest level of care."

-- Richard Sisk can be reached at Richard.Sisk@Military.com.