President Donald Trump has given the U.S. military the green light to take control of federal land along the southern border with Mexico.

In a memo sent to key departments — Defense, Interior, Agriculture, and Homeland Security — Trump announced a new mission called “Military Mission for Sealing the Southern Border of the United States and Repelling Invasions.” This means the military will now have the power to use certain federal lands along the border.

The order also allows the Secretary of the Interior to set aside or change how public land is used so the military can better use it for defense purposes.

Trump explained that the southern border is facing many threats and said the situation is serious. He believes the military needs to take a stronger role in protecting the country’s border than it has in the past.

He also said the Constitution gives him the power to take actions he believes are best for protecting the country.

This new military directive includes land like the Roosevelt Reservation — a 60-foot-wide strip of federal land created in 1907 by President Theodore Roosevelt. It stretches for about 700 miles along the border with Mexico.

The order is aimed at improving border security by using military support directly on federal land.