Military experts have explained which Americans would be called up first if the United States reinstated compulsory military service during a major international conflict.
Questions about a potential military draft have resurfaced amid tensions involving the United States and Iran, with concerns about what could happen if the fighting escalated into a wider war.
The discussion comes after Donald Trump's Republican Party suffered significant losses in the November 2026 midterm elections, changing the balance of power in Congress.
Although the US military currently operates on a voluntary basis, the country maintains a registration system designed to help the government mobilise additional personnel during a national emergency.
And with changes to that system scheduled to take effect in December 2026, experts have outlined how Americans could be selected if conscription were ever reinstated.
Which age group would the US military draft first?
Under the existing Selective Service system, men who turn 20 during the year of a military draft would receive first priority.
That does not mean every 20-year-old would automatically be required to serve.
Instead, eligible men in that age group would enter a lottery designed to determine the order in which they could be called for assessment.
Guido Rossi, a research fellow at the University of South Florida's Global and National Security Institute, explained the system to The Mirror.
According to Rossi, the first priority would be 20-year-olds, followed by men aged 21 through 24, with additional age groups considered if more personnel were needed.
The full order outlined by the Selective Service System is:
The system is designed to establish an orderly selection process rather than automatically recruit everyone within a particular age group.
Why would 20-year-olds be selected before younger men?
Rossi explained that the preference reflects a combination of military considerations and historical American approaches to conscription.
He suggested that 20-year-olds are considered an age group capable of meeting demanding physical requirements, while the system also attempts to avoid selecting the youngest eligible men first.
The researcher described the approach as a balance between physical readiness and a tradition of shielding younger men from overseas combat.
However, being selected through the lottery would not guarantee deployment into a combat role.
Individuals would still undergo assessments, and military assignments would depend on their eligibility, training and the armed forces' requirements.
What is changing about US military draft registration?
A significant change to the Selective Service registration process is scheduled to take effect on December 18, 2026.
Under legislation signed by President Trump in December 2025, the Selective Service System will move towards automatically registering eligible men using information obtained from federal government records.
Previously, most eligible men were responsible for registering themselves, usually shortly after turning 18.
The new system shifts much of that administrative responsibility to the federal agency.
The change is intended to improve registration coverage and reduce the need for individuals to complete the process themselves.
However, automatic registration does not mean automatic conscription.
The legislation does not itself authorise the government to begin drafting Americans into military service.
It changes how the government maintains its database of potentially eligible individuals, not whether those individuals must immediately join the armed forces.
Who is required to register for Selective Service?
Under current rules, almost all male US citizens and male immigrants living in the United States between the ages of 18 and 25 must register with the Selective Service System.
This includes US-born citizens, naturalised citizens, lawful permanent residents and many undocumented immigrants.
Male US citizens living abroad are also generally required to register.
Some exemptions apply, including certain foreign nationals who are lawfully present in the United States on qualifying nonimmigrant visas.
Women are not currently required to register under the federal Selective Service law.
Registration does not establish that a person is medically qualified for military service, nor does it mean they would necessarily be drafted during an emergency.
Could millions of Americans be called into military service?
Christopher Lee, of Foresight Strategic Advisors, told The Mirror that millions of men are included in the potential registration pool.
Citing figures from the Selective Service System, he said approximately 15 million men were registered within the relevant age range.
He suggested the wider pool could be closer to 18 million when accounting for those who had not registered.
However, Lee stressed that the number actually called into service would likely represent only a small proportion of that total.
Military eligibility also depends on factors including medical fitness and other legal requirements.
Rossi estimated that a substantial proportion of men within the relevant age range might not meet current military entry standards.
Those standards could potentially change during a major national emergency, but no such relaxation should be assumed.
Could the US bring back the draft because of Iran?
Despite concerns about the possibility of a wider conflict, experts have cautioned against assuming that military conscription is imminent.
Lee suggested that a conflict focused primarily on air operations and naval activity would not necessarily require the large numbers of additional ground personnel associated with a military draft.
He argued that the practical difficulties of a major ground invasion of Iran would make such an operation especially challenging.
His assessment was that a draft would be unlikely in a conflict largely conducted through air and naval forces.
That remains an expert opinion rather than a guarantee about future military decisions.
What would need to happen before Americans could be drafted?
The United States has not conducted a military draft since 1973, when conscription ended during the Vietnam War era.
Today, reinstating a draft would require authorisation from both Congress and the president.
If a draft were authorised, the Selective Service System would activate procedures for selecting potential recruits.
A publicly conducted lottery would establish the order of selection using birth dates.
Selected individuals would then be directed to undergo further screening to determine whether they were eligible for induction.
They could also seek applicable exemptions, postponements or deferments under the rules governing the draft.
Conscientious objectors may qualify for alternative service arrangements depending on their circumstances and the applicable legal requirements.
Simply appearing in the Selective Service database would not automatically result in someone being sent overseas.
Could Americans refuse to serve if a draft was reinstated?
Failing to comply with a lawful military draft could carry serious legal consequences.
However, the Selective Service system includes procedures for reviewing claims involving medical conditions, hardship, conscientious objection and other recognised circumstances.
Individuals would need to follow the relevant procedures and provide supporting information where required.
The rules for registration and the rules governing actual induction are separate, meaning someone who is required to register may not ultimately be required to serve.
Is the US military draft being reinstated?
There is currently no active military draft in the United States.
The scheduled introduction of automatic Selective Service registration is an administrative change, not an announcement that compulsory military service is beginning.
Although international tensions have prompted renewed public interest in conscription, the United States continues to rely on volunteer military personnel.
If Congress and the president were ever to authorise a draft, the existing system would prioritise men turning 20 during the selection year, followed by other eligible age groups.
For now, the distinction between registering for a possible future draft and actually being called into military service remains essential.
