US Defence Secretary Pete Hegseth has introduced mandatory testosterone screening for active-duty service members aged 30 and older, framing the policy as a combat-readiness measure — and reigniting a global debate about whether declining male hormone levels could ultimately accelerate the shift toward robot-led warfare.

The Pentagon's new screening mandate

Announcing the programme earlier this month, Hegseth said it would help ensure troops remained 'strong, resilient and capable'. He argued that the demands of modern warfare required 'maximum psychological and mental readiness'. The US Defence Secretary also stressed that the initiative had 'nothing to do with artificial enhancement', seeking to draw a clear line between diagnostic screening and performance-boosting intervention.

The policy applies across the US Army and other active-duty branches, marking one of the first institutionalised efforts by a major military to formally monitor hormonal health as a component of operational fitness.

Why it matters: A global hormone decline in focus

Male testosterone decline is increasingly recognised as a worldwide phenomenon, drawing concern from medical communities, governments, and now militaries. The Endocrine Society has documented a long-term downward trend in average testosterone levels among men in multiple countries, attributing the shift to factors including obesity, sedentary lifestyles, environmental exposures, and chronic stress.

In China, experts have raised similar alarms, with some arguing that sustained hormonal shifts could carry strategic implications for future military planning. The intersection of biology and battlefield doctrine is no longer a fringe discussion — it is entering mainstream defence policy circles.

The competitive backdrop: Robot wars as the logical endpoint

A urologist at Shanghai First People's Hospital, one of mainland China's top-tier medical institutions, offered a blunt assessment of where this trajectory leads. 'From now on, it will all be robot wars,' the doctor said, speaking on condition of anonymity due to the sensitivity of the subject. 'No matter how developed the muscles of carbon-based life forms are, they can't defeat robots,' the physician added.

The International Federation of Robotics has tracked rapid growth in military and industrial robotics deployment globally, a trend that lends weight to such projections. Autonomous systems, drones, and AI-enabled platforms are already reshaping doctrine at the Pentagon and among rival militaries.

What's next: Policy, biology, and the battlefield

The testosterone screening programme faces scrutiny from Democratic lawmakers, who have questioned its scope and implications for service members' privacy and medical rights. Meanwhile, debate continues over whether testosterone replacement therapy — flagged under programmes like TRT and HRT — would be offered to those who screen below threshold, or whether the data would simply inform fitness evaluations.

Standards such as those maintained at US Ranger School — among the most physically demanding in the military — will serve as a benchmark against which any hormonal intervention policy will be measured. As robot warfare capabilities advance and human biological baselines shift, the question of who — or what — fights future wars is moving from science fiction to strategic planning.