SAN DIEGO (AP) — As President Donald Trump announced his plans for a wall on the US border with Mexico, border patrol agents in San Diego on the lookout for drugs and smugglers drove all-terrain vehicles along a barrier that reaches 18 feet, topped by razor wire and reinforced by cameras and lighting.

Mexicans shopped at an outlet mall that bumps up against the border. And dozens of migrants huddled in tents outside a shelter in Mexico hoping to get into the US someday.

To them, Trump’s executive order Wednesday to build a wall seemed more like a symbolic and worrisome gesture of a new chapter in US-Mexico relations than a real deterrent for people to enter the country illegally.

“Even if they build the wall, I will climb the wall. I bring a ladder the size of the wall, even from sticks or whatever, but I’ll make it, and I’ll jump over there,” said José de Jesús Ramírez, a recently deported Mexican migrant whose wife and children are in the US.

Ramirez’s response echoed the mood along the border that was a combination of resentment, defiance and business as usual. A crew of labourers was actually building a fence on the border as Trump made his announcement. On a cold morning in the desert, the workers installed concrete blocks on which the 22-foot steel fence will stand between the town of Sunland Park, New Mexico, and Ciudad Juarez in Mexico. The project has been underway for several months.

In Tijuana, a high school student went to a stone monument dedicated by both countries in 1848 as a sign of the friendship between the US and Mexico. The monument once stood on the border but now is in Mexico, a few feet away from a giant wall of towering steel bars that lead into the Pacific Ocean.

The student, 17-year-old Brandon Dzul, said talk of another wall stirred up painful memories of his 34-year-old uncle who died in the desert six years ago after being abandoned by smugglers.

“He just had the American dream, you know, to make a better life,” he said. “I think now we aren’t going to be able to get in even with a visa.”

Nearby, about 150 people gathered in tents outside a 40-bed migrant shelter that has been overwhelmed since May, when large numbers of Haitians began stopping in the Mexican border city on their way to the United States. Many moved to Brazil after Haiti’s 2010 earthquake and went north after jobs dried up in the South American country.

Haitians generally turn themselves in to US inspectors at San Diego’s San Ysidro port of entry, the nation’s busiest crossing, making no attempt to jump the fence or evade authorities. They were released on humanitarian parole until September, when the US ended special treatment for Haitians and began deporting them just as they do people from other countries.

US authorities lack resources to process Haitians quickly enough, leading Mexican authorities to create a ticketing system that leaves them waiting in Tijuana for weeks. Migrant shelters are full, forcing many to sleep on the streets.

Fences and other barriers already blanket about 700 miles of border, much of it in California and Arizona. In San Diego, they helped to virtually shut down what was the busiest corridor for illegal crossings in the 1990s. It’s now one of the most fortified stretches of landscape on the 2,000-mile divide between the two countries.

Border Patrol sector chiefs were asked in November to identify areas where the fence could be expanded, though Trump and his advisers have yet to detail their next steps. Brandon Judd, president of the National Border Patrol Council and a member of Trump’s transition team, supports building a wall in strategic locations and reinforcing existing barriers in certain areas but not where there are natural obstacles, like the Rio Grande river in Texas.

“We do not need a Great Wall of China from California to Texas,” Judd said in an interview last week.

Away from the border, Trump drew support from his base. Tammy Allen, a 52-year-old supporter who splits time between Florida and Virginia, applauded Trump’s interest in curbing the number of refugees coming to the US and building a wall.

“A lot of countries do. Why not us? Something has got to be done,” she said.