US defense secretary Pete Hegseth's order mandating testosterone-deficiency screening for all active-duty and reserve service members aged 30 and above has drawn criticism from several medical experts, who question the scientific basis of the policy.

US Defense Secretary says plan is 'about restoring and optimising ... natural capabilities' of troops.

Secretary of Defense Pete Hegseth has announced that all service members aged 30 and older will undergo mandatory screening for testosterone deficiency.