US military troops come in active-duty, Guard, and reserve forces. Here's what each one does.

Yahoo

09-02-2025

The National Guard, rooted in colonial militias, serves state needs under governors.
Active-duty and reserve forces operate under federal command. Sometimes the National Guard can too.
Different laws govern when a president "federalize" the Guard, with special circumstances.
The US military fights wars abroad, but it also keeps busy back home. There are different types of forces, though, and rules on what they can and can't do on domestic soil can be confusing.
The past few months alone have seen a lot of activity. Active-duty troops are transporting migrants as part of new White House deportation measures, with others deployed to the US-Mexico border. Their counterparts in the National Guard are also active at the border. Other Guard units have helped battle wildfires and assisted with hurricane recovery.
The National Guard traces its roots all the way back to colonial America.
"The best way to think of the Guard is as a classic citizen-soldier," Rachel VanLandingham, a national security expert and professor at Southwestern Law School, said. Those state militias have transformed over 250 years into individual state National Guards, with around 430,000 members collectively across the nation.
The Guard is made up of regular community members such as teachers, bankers, social workers, and so on who can be called up to respond to emergencies at the discretion of their state governors. "When there's a need, they're gonna put on a uniform," VanLandingham said. "But they specifically belong to the state."
There are generally two categories of people who join the National Guard, said Katherine Kuzminski, who oversees the Center for a New American Security's military, veterans, and society program.
Most National Guard troops are either pursuing a civilian career but still want to serve or were once on active duty but are now part-timers.
Like the reserves and active forces, National Guard troops go through basic training with follow-on specialized job training. They hold specific military jobs, which can include anything from truck mechanic or pilot to infantryman or admin specialist.
Because active troops are assigned to military bases that are usually far removed from heavily populated areas, leading to less overlap with civilians, most Americans rarely engage with active troops, and are more likely to know someone who's in the Guard or the Reserve.
Similar to the Guard, reserve forces are the part time equivalent of the active-duty force. Many reservists are also former full-time troops who were once on active duty. Reservists frequently belong to units based outside their home states, meaning they might travel monthly to "drill," performing routine duties to stay fresh in uniform.
Both Guard troops and reservists are usually obligated to serve one weekend a month in uniform and then at least two consecutive weeks yearly to maintain military skillsets.
Active-duty service members enlist for a specific number of years, with options to extend. They live on or near the military base to which they are assigned. Most active service members work normal workdays but are expected to undergo long training exercises, perform overnight duties, and are often on call 24/7.
The most important differences between Guard, reserve, and active-duty forces are in their chains of command and legal authorities.
First, the chain of command for all reservists and active troops is entirely through the Department of Defense, up to the service secretaries and the president. States have no control over reserve forces.
Each of the armed services under the Department of Defense has its own reserve component, but only the Army and Air Force have National Guards. States have not historically needed naval forces, Kuzminski said, so the Department of the Navy (which includes the Marine Corps) doesn't have a National Guard component. Right now, there isn't a Space Force National Guard either.
Reservists also have the option to "activate," which means that they can become active duty for a set period of time, either deploying abroad or reporting daily to a base stateside for set periods of time. "Activating" can be a popular choice for reservists seeking stability amid economic uncertainty in their civilian work or who are simply eager to deploy and serve.
National Guard control is different and a little confusing.
Most of the time, the National Guard operates under the purview of their state's governor, VanLandingham said. When called by the governor, Guard troops most often are responding to natural disasters or emergencies, like those in North Carolina who responded to Hurricane Helene last year or those in California who activated in response to the recent fires. National Guard troops were also deployed to the Capitol on January 6, 2021, amid riotous efforts to contest the election.
"Guardsmen belong to a service, but their chain of command goes to their governor," Kuzminski said.
A president or governor can request to "federalize" their guard troops, putting them on loan to the nation. When the Guard is federalized, those troops swap to operate under different laws that govern the rest of the DoD, known as Title 10.
Federalized Guard troops were vital for the Global War on Terror, said Kuzminski. Hundreds of thousands deployed over the years.
But federal adherence to the legalese that governs Guard operations has made headlines in recent years. During President Donald Trump's first term, he brought in unfederalized, out-of-state Guard troops to Washington, DC, a non-state jurisdiction, to quell protests. Some experts said the move jeopardized laws preventing the unconstitutional use of troops at home.
Governors can activate their National Guard troops to serve in certain domestic law enforcement roles at home, but all of the key constitutional guarantees still matter, VanLandingham said. "It's not like different rules apply."
The Posse Comitatus Act bars federal troops from participating in this role though. To circumvent Posse Comitatus, presidents can lean on the Insurrection Act. Trump has repeatedly floated the idea of using the military at home more recently, leading some legal experts to say the Insurrection Act is overdue for reform.
Read the original article on Business Insider