U.S. Declares Large Naval-Controlled Defense Zone Along California-Mexico Border

SANTA FE, N.M. — The Trump administration has designated a large portion of California’s international border with Mexico as a national defense area, transferring jurisdiction over much of the region to the U.S. Navy to support border-security operations.

Scope of the Designation: The newly created defense zone stretches nearly from the Arizona state line to the Otay Mountain Wilderness, cutting across the Imperial Valley and touching border communities such as Tecate. The Interior Department described the corridor as a high-traffic area for unlawful crossings.

Military Role and Capabilities: Since April, several broad swaths of the southern border have been declared national defense areas. That designation allows U.S. troops on Army, Air Force or Navy lands to detain migrants and others accused of trespassing and authorizes additional criminal charges in some cases. Officials say more than 7,000 troops have been deployed to the border, supported by helicopters, drones and other surveillance equipment.

Origins and Expansion: The operation began in April along roughly 170 miles of border in New Mexico and was subsequently expanded to portions of the border in Texas and Arizona. The California announcement represents the latest extension of the strategy.

Legal experts warn that using the military in this way risks violating prohibitions on domestic law enforcement by the armed forces and could politicize military missions.

Political and Legal Fallout: The designation comes amid a broader emergency declaration that has placed the military at the center of efforts to deter migrant crossings between official ports of entry. Critics and legal scholars argue that the policy may conflict with long-standing limits on the military’s role in domestic law enforcement.

Separately, a federal judge recently ordered the administration to stop deploying the California National Guard in Los Angeles and to return control of those troops to state authorities. Earlier in June, the president activated more than 4,000 members of the California National Guard without the approval of Governor Gavin Newsom to assist federal immigration-enforcement operations.

Outlook: Supporters say the transfers close security gaps and protect public lands; opponents warn of legal challenges and the potential for strained federal-state relations as courts and state officials press back.