US Defence Secretary Pete Hegseth announced on Wednesday mandatory annual testosterone screening for troops 30 years old or above, an initiative he said was aimed at combating testosterone deficiency that can undermine health.

Hegseth said the screening could lead to troops being offered testosterone replacement therapy aimed at “ensuring you have the right testosterone levels to operate at your absolute best”.

“Because it’s well-established science that as we age, testosterone levels often naturally drop,” he said in a video message.

The screening would become part of annual testing for troops aged 30 and above, and troops could voluntarily decide whether to accept any recommended hormone replacement treatment if they were diagnosed with low testosterone levels. Troops below the age of 30 could request to be tested.

The move comes as the US Department of Health and Human Services has moved to ease some restrictions on testosterone replacement therapies, including announcing last month it would seek to remove limits on use in men with age-related low testosterone.

Still, Hegseth’s announcement triggered backlash from opposition Democrats, who pointed to his ban on transgender service members who often depended on hormone therapy.

“So now y’all support gender-affirming care?” Democratic Congresswoman Summer Lee said.

“Sounds like gender-affirming care to me,” Senator Tammy Duckworth added.