LOS ANGELES, Dec. 19 (Xinhua) -- About 500 Marines from Camp Pendleton in Southern California are being deployed to Yuma, Arizona, to support security along the U.S.-Mexico border, the San Diego Union-Tribune reported Friday.

The report quoted words from the base as saying that the troops' mission would focus on reinforcing barriers, placing signs, and monitoring and detection along the border since military personnel are not authorized to conduct civilian law enforcement activities such as search, seizure or arrests.

However, the report said such deployments had been common over the past year under U.S. President Donald Trump as some swaths of land along the Arizona border, including near Yuma, had been designated as a National Defense Area (NDA) as part of Trump's crackdown on illegal immigration.

NDA is a Trump administration designation creating a militarized zone along the southern border with Mexico, transferring land to the Department of Defense for enhanced security with military-grade surveillance, including drones, sensors, troops, barriers like walls/razor wire and enforcement.

The designation allows troops to detain people suspected of trespassing onto a military base and turn them over to federal law enforcement. People who are arrested can face federal trespass charges.

The newest such militarized border zone is in California's Imperial County and the eastern parts of San Diego County. ■