More than illegal immigrants who try to cross the border, more than drugs, what worries Homeland Security Secretary John Kelly is the criminal network that lays all of it on America's doorstep.
"We've made a difference, to say the least, on the southwest border," Kelly said Tuesday of the Trump administration's nascent efforts to enhance security. "But this network is so well-developed and is so efficient, it can move anything."
According to the Department of Homeland Security, the network used by criminal cartels and smugglers has moved hundreds of tons of drugs into the U.S. And until recently, it was also moving tens of thousands of illegal immigrants.
"But it could move other things, too," Kelly told an audience Tuesday at George Washington University, suggesting biological weapons or even a dirty bomb would not be out of the question.
"There's a lot of subcontractors in this network, and these guys don't check passports. They don't do explosive residue testing," Kelly continued. "If you've got the money, you're in."
Concerns in Europe
The threat is not necessarily unique to the United States. European security officials have voiced similar concerns in the past, especially following the initial waves of refugees that poured into Europe from places like Syria and Libya.
Intelligence officials have also long suspected that terror groups, like Islamic State, made expert use of such criminal networks to sneak foreign fighters through Turkey in order to bolster their numbers as much of Syria fell into chaos.
Such networks have even played roles in helping terrorists across North Africa and the Middle East launder money, profit from the drug trade and secretly build their fortunes.
Steadily, signs of higher levels of sophistication have been emerging, with officials from Europe and the East Asian Pacific pointing to people smugglers in the Middle East and South Asia.
"In countries like Pakistan, the traffickers or the migrants compare and benchmark: Is it now a better time to go to Europe or better to go to Australia?" Fabrice Leggeri, executive director of Frontex, the European border and coast guard agency, told VOA late last year. "So one can imagine there is a sort of global market."
American officials worry that with Islamic State's self-declared caliphate falling apart, the pressure to make even better use of these networks is only likely to increase, especially as once-loyal foreign fighters start to think about making their way to the U.S.
"We're already seeing large numbers of the fighters go home," Homeland Security's Kelly warned Tuesday, expressing specific concern about those aiming to return to European countries that have visa-waiver agreements with the U.S.
Yet, thanks to the growing synergy between criminal networks and terrorists, even those foreign fighters who are not able to use Europe as a gateway can still wind up on America's borders.
There is a chance, U.S. officials warn, that some already have.
"The nexus between criminal networks and terrorist networks is real and, I would predict, will get more sophisticated," Kelly cautioned. "They're not doing it in huge amounts yet, I don't believe, but to me, it would be a next step."