Explainer-What are US troops doing in Los Angeles?

WASHINGTON (Reuters) -U.S. President Donald Trump's administration has said it is going to deploy 4,000 National Guard troops and 700 Marines to Los Angeles to help protect federal property and personnel during the ongoing protests in the city.

Here is everything we know about the U.S. troops that are being deployed to Los Angeles:

WHAT ARE THE DIFFERENT TYPES OF TROOPS SENT TO LA?

National guard troops usually belong to individual states and personnel in many cases are trained to help with emergencies that those states have to deal with, such as natural disasters.

Since they are the reserve force of the U.S. military, National Guard troops are usually part time, meaning that they have other jobs as well.

U.S. Marines on the other hand are active duty troops - it is a full time job.

Marines are trained for conflicts around the world - from the Middle East to Africa - and are used for rapid global deployments in case of emergencies, such as threats to U.S. embassies.

All those troops will come under a task force, known as Task Force 51.

HOW CAN TROOPS LEGALLY BE DEPLOYED WITHIN THE UNITED STATES?

Trump cited Title 10 of the U.S. Code, a federal law that outlines the role of the U.S. Armed Forces, in his June 7 order to call members of the California National Guard into federal service.

A provision of Title 10 - Section 12406- allows the president to deploy National Guard units into federal service if the U.S. is invaded, there is a "rebellion or danger of rebellion" or the president is "unable with the regular forces to execute the laws of the United States."

The president also has the authority to deploy active duty troops, like the Marines, within the United States in limited cases.

WHERE ARE THE TROOPS COMING FROM?

Many of the 4,000 National Guard troops are coming from the California National Guard. So far, 2,100 soldiers from the 79th Infantry Brigade Combat Team, a unit of the California National Guard, are on the ground.

The Marines being deployed are from the 2nd Battalion, 7th Marines, 1st Marine Division. They are based out of Twentynine Palms, close to Los Angeles.

WHAT CAN TROOPS DO AND WHAT CAN THEY NOT DO?

Both National Guard troops and Marines will be carrying out the same tasks, according to U.S. Army Major General Scott Sherman, who is commanding the troops.

They are tasked with protecting federal property and federal personnel. This means that they will accompany ICE agents on raids, officials have said.

The troops are authorized to detain people who pose a threat to federal personnel or property, but only until police can arrest them. Military officials are not allowed to carry out arrests themselves.

The Posse Comitatus Act, generally forbids the U.S. military, including the National Guard, from taking part in civilian law enforcement.

Trump could take a more far-reaching step by invoking the Insurrection Act, which would allow troops to directly participate in civilian law enforcement.

WHAT TRAINING WILL THE TROOPS RECEIVE?

Troops receive varying levels of training in dealing with riots and crowd control.

Since National Guard troops are used domestically in many cases, they receive extensive training when it comes to crowd control and civil unrest.

While Marines may receive a basic level of crowd control training, it is not their expertise in domestic situations. The 700 Marines will receive two days of training focused on civil disturbance, crowd control and protection of facilities, before they are deployed to the streets of Los Angeles.

The Marines will also have added "legal and law enforcement expertise," the military said.

WHAT WILL TROOPS BE ARMED WITH?

National Guard troops have been seen carrying shields, batons and rifles, along with regular protective equipment.

The Marines will also be armed with riot shields and batons, and Sherman said they will not have ammunition in their rifles, but they will carry it.

(Reporting by Idrees Ali, editing by Michelle Nichols and Michael Perry)