Thursday, November 12, 2026
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Trade & Customs Nov 12, 2026 · 7 min read

US and Mexico close in on transshipment

Tracker Section 232 tariffs list · 9 groups

Mismatched paperwork, not tariff rates, is now what stops cargo at the Mexican border

US and Mexican customs officers offloaded and inspected 80% of the shipments they targeted in a five-day joint operation at the Otay Mesa cargo export facility near San Diego. Sandler, Travis & Rosenberg (STR), a US trade law firm, reported the result on 10 November 2026.

The operation was run by US Customs and Border Protection (CBP) and Mexico’s national customs agency, the Agencia Nacional de Aduanas de México (ANAM). It looked at in-bond shipments moving between the two countries. In-bond means goods travel under a customs bond, a guarantee to customs, without being formally entered or paying duty at the first port. The main focus was high-value electronics and textiles.

A day later, Mexico’s deputy economy minister for foreign trade, Luis Rosendo Gutierrez, told Reuters that Mexico had removed about 1,100 steel mills from its approved registry. Many were in Asia. Mexico found they “did not actually exist.”

What we think this means

Our view is simple. Along the US–Mexico border, the transshipment fight has moved from tariff rates to data matching. Transshipment means routing goods through a third country to hide where they were really made, usually to dodge a higher duty.

For years the main tool was a higher tariff on the country of origin. That only works if the stated origin is true. What Otay Mesa shows is two customs agencies checking each other’s records on the same shipment. A false origin claim has to survive both systems now, not one.

Mexico has its own reason to help. It wants relief from US Section 232 tariffs. These are duties the US imposes on national-security grounds, and they currently hit Mexican autos, steel and aluminium. Shutting down the backdoor for Asian steel is Mexico’s main bargaining chip. We think the joint sweep and the registry purge are part of the same trade: enforcement now, in return for tariff relief later.

What the operation found

STR’s report sets out the targets. The agencies were looking for possible transshipment, undervaluation, inaccurate country-of-origin claims and customs documentation errors. Undervaluation means declaring goods at less than their real value to cut the duty owed.

CBP said these practices can undermine legitimate trade and evade lawful duties, and “result in significant revenue losses for both countries.”

The method matters most for forwarders. STR describes “the enhanced real-time exchange of information between the two customs agencies”. Officers compared US export records, commercial documents such as invoices, and Mexican customs data side by side.

What they found falls into five areas: value, classification, merchandise descriptions, quantities and country of origin. Classification means the tariff code, known in the US as the HTS (Harmonized Tariff Schedule) number. STR says the shipments showed discrepancies or indicators that need more review. It does not say how many shipments were involved, or whether any were seized. It also gives no dates for the five days. CBP announced the result “recently”, according to STR.

The work is not finished. CBP said it will coordinate with ANAM on follow-up reviews. These include checking manufacturers, importers, exporters and the origin documents they rely on. The two agencies plan to widen data sharing, coordinate targeting and speed up trade data checks. CBP said these efforts “will help both agencies detect and disrupt sophisticated commercial-fraud schemes”, including improper claims under USMCA, the US–Mexico–Canada trade agreement.

Mexico’s side: 1,100 mills that were not there

The Reuters report, by Kylie Madry and published on 11 November, adds Mexico’s numbers.

Gutierrez said Mexico had tightened traceability, meaning the ability to track a product back to where it was made. He said “there is no triangulation of steel or other products” reaching the US through the trade agreement. Triangulation is another word for transshipment.

According to Reuters, he gave three figures:

  • About 1,100 steel mills, many in Asia, removed from Mexico’s approved registry because they did not exist.
  • Steel imports from Vietnam down 80% over the past several months.
  • Steel and aluminium imports from third countries, including China, South Korea and India, down about 30%. That is roughly 13 billion pesos, or about $698.54 million.

These are Mexican government figures. Reuters did not publish an independent check of them.

Gutierrez also said about 80% of Mexican exports to the US already enter tariff-free. So Mexico’s priority is not a broad rewrite of USMCA. It is cutting the impact of the Section 232 tariffs on autos, steel and aluminium. He said US officials had welcomed proposals from Economy Minister Marcelo Ebrard. Reuters reports that Mexico “hoped for positive news in the coming weeks before year-end.” No deal has been announced.

How we got here

This did not start in November. On 1 January 2026, Mexico put tariffs of 5% to 50% on 1,463 product categories from countries it has no trade deal with, Mexico News Daily reported. Those include China, India, South Korea, Thailand and Indonesia. The covered sectors include steel, aluminium, textiles, clothing, autos, plastics and footwear. The government expected the duties to raise an extra 70 billion pesos ($3.8 billion) a year.

That was the tariff wall. The registry purge and the joint sweep are the inspection of the gate. Mexico first raised the cost of bringing Asian goods in. Now it is checking whether the goods that do come in are what the paperwork says.

Not everyone thinks Mexico was a big leak to begin with. Reuters notes that analysts argue Mexico is “not a hub for steel” transshipment. But it also cites a report by the Center for Strategic and International Studies (CSIS), a Washington think tank. That report said some goods may go through significant processing in Mexico before export to the US. That grey zone is exactly where origin rules get tested. Is a product made in Mexico, or only finished there?

The wider calendar is slow. A weekly digest from Puente LATAM, a Latin America policy newsletter, said on 10 November that, according to Economy Minister Marcelo Ebrard, Mexico has held three rounds of the USMCA review. The fourth was delayed until after the US election. The digest gives no new date. Comments for the USMCA joint review are due on 12 January 2027. The same digest notes the Section 232 duties rest on presidential authority. It says changes are more likely to come through executive negotiations, litigation or the USMCA review.

What forwarders and shippers should do

The practical point: the three documents on a cross-border move now get read together. The US export filing, the commercial invoice and the pedimento must tell the same story. The pedimento is the Mexican customs declaration. Value, tariff code, description, quantity and origin all need to match. At Otay Mesa, mismatches in those five areas are what led to cargo being pulled off.

Some steps follow from that, in our view:

  • Check in-bond moves first. The sweep targeted in-bond freight between the two countries. Electronics and textiles were the focus. If you run these moves, review recent files now.
  • Line up tariff codes. US and Mexican codes share the same first six digits under the global system. Differences after that are normal. Differences in the first six digits are a red flag.
  • Have origin proof ready. CBP plans to verify manufacturers and origin documents. Shippers claiming USMCA preference should expect requests for supplier records. Forwarders should help clients collect them before a letter arrives.
  • Watch the steel and aluminium supply chain. Mexican mills buying Asian inputs face a shorter approved supplier list. Expect longer lead times and more paperwork on metals moving north.
  • Budget for inspection time. If 80% of targeted loads get offloaded, a flagged shipment can lose days. Build that into delivery promises on high-value cargo.

If a Section 232 deal does come, it would change landed costs on Mexico-built cars, steel and aluminium. That would add volume to the northbound truck and rail lanes that serve them. We would not plan around that yet.

Our prediction

Our call has two parts.

First, no cut to Section 232 tariffs on Mexican steel will take effect before 31 December 2026. Mexico says it hopes for positive news in the coming weeks. But no deal has been reported. No date has been reported for the fourth USMCA review round. The next formal milestone, joint review comments, falls on 12 January 2027. At most, we expect an announcement of a framework, such as a quota, before year-end, with any lower rate starting in 2027.

Second, CBP will announce at least one more joint trade enforcement operation with ANAM at a different border crossing by 31 March 2027. Both agencies have said they will widen data sharing and coordinate targeting. Mexico needs to show results to win tariff relief. Repeating the Otay Mesa model at a bigger crossing is the cheapest way to do that. We expect electronics, textiles and metals to stay the focus.

Sources

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