Border Patrol agents uncovered a tunnel in San Diego early Saturday that they said was used to smuggle illegal immigrants across the border - a rare tactic that suggests the cartels that control illicit traffic from Mexico to the U.S. are searching for new methods.
Cartels have long used tunnels as pathways for drugs, while migrants generally have been smuggled above ground.
The drug smuggling, meanwhile, is increasingly taking to the air. Agents this month nabbed a drone in San Diego that was carrying methamphetamine and last week saw a 96-pound load of marijuana being fired over the border fence in Douglas, Arizona.
The smuggling attempts were reported even as the first phase of President Trump's border fence got back on track Friday. U.S. Customs and Border Protection, the agency overseeing the project, said the government had dismissed a protest filed against the contracting process and finalists will soon be awarded.
That will accelerate the schedule for building prototypes, which had appeared ready to slip into November.
"This means that we are now able to award contracts as soon as we are ready. We therefore expect to make awards soon," CBP said in a statement.
The wall was one of Mr. Trump's most prominent campaign promises, though it has proved to be controversial.
CBP already has $20 million in the pipeline to build prototypes but does not have funding to begin construction of real fencing.
Democrats and even some Republicans on Capitol Hill question the use of more barriers along the border.
Mr. Trump has said he is willing to face a government shutdown to get additional money, and Democrats have also signaled they are willing to shut down the government rather than fund the wall.
The wall was unable to stop this weekend's tunnel, which stretched from Tijuana underneath the border - and two types of fence systems on the U.S. side - before popping up in an area full of warehouses.
Agents sniffed out the tunnel after spotting several illegal immigrants on the U.S. side of the border near the Otay Mesa port of entry just after 1 a.m. Saturday. Some of the migrants ran back for the tunnel, according to local news reports.
Agents arrested 30 illegal immigrants connected to the tunnel. They were 21 Chinese men, two Chinese women, four Mexican men and three Mexican women.
"While subterranean tunnels are not a new occurrence along the California-Mexico border, they are more commonly utilized by transnational criminal organizations to smuggle narcotics. However, as this case demonstrates, law enforcement has also identified instances where such tunnels were used to facilitate human smuggling," the agency said.
It could be another signal that the ability to smuggle people across the border is becoming harder.
The price for smuggling someone into the U.S. has skyrocketed in recent months. Mexican and Central American migrants describe prices in the $10,000 range.
Chinese migrants, meanwhile, have reportedly paid more than $50,000 for their journey over the years.
While illegal immigration across the southwestern border is down compared with a year ago at this time, the flow of drugs remains high, officials say.
Cartels have taken to using a wide range of methods to get drugs across the border, including T-shirt cannons, drones, ultralights, catapults and even cranes that swing loads from Mexico to the U.S. on their arms, then drop them for pickup.
Flinging big loads by catapult has become common in Douglas, a town in the southeastern corner of Arizona, where agents spotted a 96-pound marijuana missile flying over the wall last week.
The agency said the drugs are worth $48,000.
Nobody has been arrested in connection with that attempt.
CBP didn't say how the bundle was fired, but last month Border Patrol agents and the Douglas Police Department found a 140-pound load that they said had been shot across the fence by catapult.
Border communities are prime locations for those kinds of operations because the drugs can be launched straight into a neighborhood on the U.S. side, where someone is waiting to pick them up.
The massive loads backed up President Trump's claims in July when he cited the prevalence of drug loads being tossed over the border as another reason for his border wall. He said it's a reason to make the wall see-through.
"As horrible as it sounds, when they throw the large sacks of drugs over, and if you have people on the other side of the wall, you don't see them - they hit you on the head with 60 pounds of stuff? It's over," he said. "As crazy as that sounds, you need transparency through that wall. But we have some incredible designs."
Critics were merciless in mocking Mr. Trump at the time.
The Atlantic said he had adopted a "Wile E. Coyote" approach to border security, while Slate questioned the president's grasp on reality. Rep. Adam B. Schiff, California Democrat and a prominent Trump critic on Capitol Hill, quipped that the real question if someone had been hit was "would it be covered by Trumpcare or would Mexico pay for it?"
The Washington Post sought out scientists to calculate whether a person could heft 60 pounds of drugs over the border wall, while late-night comic Seth Meyers said Mr. Trump had entered the realm of fantasy.
"Wait a minute. Trump thinks drug dealers are going to walk up to the border wall with a 60-pound bag of drugs and then chuck it over to another drug dealer? It's official: Donald Trump thinks in cartoons," Mr. Meyers said on his NBC program.