The US air force is centralizing the way it handles the discharge of transgender personnel from its ranks in a move that forms part of the military’s inching towards a more permissive approach to gender dysphoria.

In a statement published on Thursday, the air force said that among enlisted airmen, there was no outright grounds for discharge for anyone with gender dysphoria or self-identifying as transgender. An individual would only be subject eviction from the air force if his or her condition interfered with their potential deployment or performance on active duty.

“Identification as transgender, absent a record of poor duty performance, misconduct, or a medically disqualifying condition, is not a basis for involuntary separation,” the statement said.

The statement that transgender airmen – the military’s generic term for male and female enlistees – are not liable to being sacked from the forces unless their gender identity conflicts with their performance on the job marks the most progressive language yet from air force chiefs. In the future, senior air force official Daniel Sitterly said, any move to discharge a transgender service member would have to be taken by the central air force review board, providing consistency across all commands.

The move begins to provide some clarity about the air force’s position in this vexed area. All military services have come under increasing criticism in recent months for their decades-old policy of banning the recruitment of openly transgender people into the forces.

The Pentagon still has on its official paperwork instructions to military recruiters that they should reject anyone with a “history of major abnormalities or defects of the genitalia including but not limited to change of sex”. Gender incongruence, where a person identifies with a gender identity other than what they were assigned at birth, is classified by the US military as a “psychosexual condition”.

Such a dismissive approach has earned the US military brickbats from around the world. Last year it was placed 40th out of 103 in a global league table of armed forces assessed for their inclusion of LGBT service members.

By contrast, the armed forces of countries such as Australia, Canada, Germany and the UK allow openly transgender personnel to serve.

Yet the winds of change can be detected within the US military. Sparta, a group of serving and former LBGT personnel in the armed forces, said it was aware of four or five current transgender service members who had been allowed to continue on duty by supportive local commanders.

“We are aware of some instances where a transgender service member has quietly been allowed to transition with the support of their commanders, although that hasn’t necessarily been shared all the way up the chain of command,” said Sue Fulton, a former army captain who is Sparta’s president.

The New York Times on Thursday profiled a trans man in the air force, senior airman Logan Ireland, who has been allowed to continue to serve and to wear male uniforms, though he is still referred to officially as a woman.

The confusion about the precise nature of the US military’s policy towards transgender service members shows no sign of abating in the foreseeable future. Lieutenant commander Nate Christensen, a Pentagon spokesman, told the Guardian that there was no specific review of the transgender policy under way.

However, he added that the Department of Defense was carrying out a routine periodic review of medical policy over the next 12 to 18 months. The review, which seeks to ensure the access to medical treatment in the services was up-to-date, was last carried out in 2011 and could have a bearing on the treatment of transgender personnel.