Donald Trump decided to start yesterday morning by dropping a bombshell on Twitter. According to some reports, military officials worried an actual bombshell was being dropped due to a lag in the president’s multi-tweet announcement. Instead, Trump merely announced that he was banning transgender personnel from serving in the U.S. military.

The details of the new policy are unclear though. There does not seem to have been policy process beforehand, nor implementation guidelines released afterwards. The New York Times reports Secretary of Defense James Mattis, who is currently on vacation, was informed of the decision a day before, and that he was “appalled” the decision was announced via Twitter. However, whatever Mattis’ feelings on the subject, early reports suggested the Pentagon’s press office had not been properly informed.

It is also unclear what prompted Trump’s decision. A number of people have speculated that this was the president’s attempt to curry favor with conservatives after his attacks on Attorney General Jeff Sessions. One anonymous White House official suggested the announcement would provide an electoral advantage by forcing Democrats to defend transgender military service in Rust Belt states. And Politico reported that Trump’s decision was as a result of a dispute among congressional Republicans about an amendment that would have prohibited the Pentagon from paying for gender reassignment surgery for transgender personnel. According to the report, the dispute threatened funding for Trump’s promised border wall.

What is clear is that the president’s justification for banning transgender military personnel does not hold up. In his tweet, Trump specifically cited cost concerns. However, researchers at the RAND Corporation estimated the financial costs of integrating transgender personnel when it was announced they would be able to serve openly. Their study found that the new policy might increase health care costs between $2.4 and $8.4 million dollars a year. The high end of that estimate would amount to a 0.13 percent increase in health care costs for the active-duty component of the U.S. military. To put that into context, the Pentagon spent $28 million over the course of a decade on woodland camouflage uniforms for the Afghan National Army despite less than two percent of Afghanistan being forest.

The other part of Trump’s justification implied that allowing transgender personnel to serve openly would undermine the military’s effectiveness. However, RAND’s research found issues related to transition-related care for transgender personnel could affect the deployability of, at most, 0.1 percent of the military when considering both the active and reserve components. Moreover, RAND’s case studies on other militaries where transgender personnel serve openly showed “little or no impact” on unit cohesion or effectiveness.

These types of arguments about using the U.S. military as a “social experiment” are not new, but nor are they consistent with its actual history. Beth Bailey, a University of Kansas historian who focuses on the relationship between the military and American society (and who, it is worth noting, was also my professor at Temple University) is working on a new project in which she argues that the military as an institution both affects and is affected by social change. As Bailey showed in her most recent book, the shift from the military draft to the all-volunteer force after the Vietnam War was itself a social experiment.

In other work on the history of the military’s “Don’t Ask, Don’t Tell” policy, Bailey has shown how arguments about military effectiveness and unit cohesion had sustained conservative objections to open service by homosexuals. However, these arguments ultimately laid the seeds of their own destruction as gay service members proved their worth in the wars in Iraq and Afghanistan.

However, these objections to social change in the U.S. military are not new. In a sad piece of irony, Trump tweeted out his transgender ban on the anniversary of President Harry Truman’s executive order to desegregate the U.S. military. Similar objections were raised at the time. Yet Truman was still willing to use the military as an experiment in desegregation nearly two decades before Lyndon Johnson signed the Civil Rights Act.

General Joe Dunford, chairman of the Joint Chiefs of Staff, has already stated the current policy toward transgender personnel stands until officially directed by the president to change it. As mentioned above, no specific direction has been given and it does not seem that any plans have been made to implement a new policy. At worst, the president announced a major policy with the intention of kicking thousands of active duty military personnel out of the military with no plan for coping with the costs or consequences of doing so. At best, and more likely, President Trump made an impulsive and reckless pronouncement that further demonstrated his willingness to use the U.S. military for his own personal political ends.