“They can do the embargo, and the Supreme Court didn’t touch what constitutes an emergency,” the person added, referring to the court’s February ruling striking down a large tranche of Trump’s tariffs imposed under a 1977 emergency law. “So, I think on those fronts, they’re in pretty good shape.”

An embargo puts legal restrictions on imports and exports between two countries, though the scope of the covered products can vary. The U.S. has imposed trade embargoes on countries before, including on Cuba and North Korea, but it requires a declaration of a national emergency and evidence that the country facing the embargo poses an “unusual or extraordinary threat” to U.S. interests. If challenged in court, it would be hard for the administration to demonstrate that Spain, a NATO treaty ally, represents such a threat.

And contrary to White House assertions, the Supreme Court’s majority opinion in its February ruling did not affirm the president’s ability to impose an embargo. However, Justices Clarence Thomas and Brett Kavanaugh argued in their dissenting opinions that Congress has delegated embargo powers to the president.

While the U.S. trade relationship with Spain is relatively small — it imported more than $21 billion in goods from Spain in 2025 and exported $26 billion, according to the U.S. Census Bureau — action against Madrid risks upending the U.S.-EU deal to lower the bloc’s tariffs on U.S. industrial products in exchange for a flat 15 percent U.S. tariff rate on goods coming from EU member countries.

The EU approved the lower tariff rate this month, but included several snap-back provisions that would reimpose duties on U.S. goods if the Trump administration were to increase tariffs or take other action against any member country.

“We are taking note. Everybody knows what would be at stake if any of these threats become real,” said one European Commission official. “It’s not the first threat.”