Days after the Trump administration announced it was expanding the militarized border zone into California, the country’s top border security chiefs, who toured the San Diego border Saturday, revealed few insights about what that might actually look like. White House “border czar” Tom Homan an d U.S. Customs and Border Protection Commissioner Rodney Scott used the visit to San Diego to outline the security operations implemented at the U.S.-Mexico border nearly one year after President Donald Trump took office — from increased immigration enforcement to the militarized zones that now stretch across parts of every state along the southwestern border. The latest was announced Wednesday by the Department of the Interior, which is transferring the jurisdiction of about 740 acres of public land in San Diego and Imperial counties to the Department of the Navy to establish a restricted military zone known as a National Defense Area, or NDA. The zone extends from the western boundary of the Otay Mountain Wilderness Area in San Diego County to roughly 1 mile west of the California-Arizona border, officials said. The zone includes areas near backcountry border towns, such as Tecate and Jacumba Hot Springs. The Department of the Interior referred to the area as “one of the highest traffic regions for unlawful crossings along the southern border.” The designation allows military personnel to detain migrants and others for trespassing and turn them over to border agencies if necessary, signaling the potential for troops to take a more hands-on approach to immigration enforcement. White House “border czar” Tom Homan shakes hands with Border Patrol agents after a press conference along the U.S.-Mexico border wall in San Ysidro on Saturday. (Sandy Huffaker / For The San Diego Union-Tribune) “We’ve always had the Department of Defense on the border, but when they’re on their own property, they have increased authorities and responsibilities to actually arrest for trespass just like they would on any other military base,” Scott said in a news conference. “We’ve been doing this in Texas for a while. We’re bringing it over here now.” When asked about what operations will look like in the area and about the volume of troops that might be deployed, Scott said that it could fluctuate. “The numbers will change depending on what we believe the threat and the requirement is to make sure that we have that section of the border sealed,” he said. The Union-Tribune reached out to both the Navy and Marines, which are under the Department of the Navy, for more details about the Navy’s management of the new militarized zone but did not receive any answers. “We will ask for whatever support we need from the Department of War to make sure that the people in San Diego and the people of this entire country are safe,” Scott said. In other designated areas along the southwestern border, signs have been posted warning that entering the area without authorization is prohibited. In those other states, federal prosecutors have been charging migrants caught crossing the border with military base trespass laws, which carry a sentence of up to six months in prison, on top of the standard illegal entry or re-entry charges. A U.S. Border Patrol spokesperson said Saturday that it is unclear when the defense area will be formally established in the eastern portion of the San Diego sector and the entirety of the El Centro sector, which handles Imperial County. Troops, including Marines from Camp Pendleton, have already been deployed at the California border under President Donald Trump, but in more of a background role. They have provided engineering support to Border Patrol agents and installed miles of concertina wire along the primary and secondary fences in the San Diego sector. This included the stretch where Scott and Homan delivered their remarks on Saturday. A Border Patrol security truck along the U.S.-Mexico border wall in San Ysidro on Saturday. (Sandy Huffaker / For The San Diego Union-Tribune) Both Scott and Homan, who said they began their law enforcement careers in the San Diego area, highlighted the significant decrease in illegal border crossings that has occurred in the last year. The latest numbers from CBP show a 93% drop in migrant encounters in the San Diego sector in October, the most recent month for which data is available, compared to the same month last year. Homan also acknowledged the support from the Navy and U.S. Coast Guard in maritime operations. “When we lock the border down, (we knew) they’re gonna take to the water,” he said. Border Patrol data shows that in fiscal 2025, which ended Sept. 30, there were 490 maritime smuggling events, resulting in 1,526 apprehensions. The previous fiscal year recorded 589 such incidents and 1,375 apprehensions. Federal officials also discussed immigration enforcement operations by both Immigration and Customs Enforcement and the Border Patrol. San Diego Border Patrol Chief Justin De La Torre previously said that the shift at the border has allowed their agents to patrol the interior more proactively. Community groups that monitor immigration operations throughout the county have noted an increased presence of Border Patrol alongside ICE agents. “We’re in a position now where the Border Patrol can actually come to the interior because the border is the most secure ever,” Homan said. Homan said that as federal agencies ramp up interior operations, the number of illegal border crossings went down. “And they’ve stayed down because the message sent to the world was we actually believe in the laws that we have in place,” he said. Staff writer Gary Robbins contributed to this report. ...read more read less