Orange no-entry signs posted by the U.S. military in English and Spanish dot the New Mexico desert, where a border wall cuts past onion fields and parched ranches with tufts of tall grass growing amidst wiry brush and yucca trees.

The fourth national defense area created along the US-Mexico border will be an extension of Marine Corps Air Station Yuma in the Sonora Desert.

Annexed militarized zones on public land will soon cover nearly one-third of the U.S. border with Mexico, empowering soldiers to arrest people who cross the border illegally and facilitating new crimi