The agreement

The Agreement on Defense Cooperation between the United States and Spain was first signed in 1953, when Spain was a dictatorship and the US needed somewhere to park bombers within range of the Soviet Union. The deal has been renegotiated and renewed several times since — most recently in 2015 — but the basic plumbing has stayed roughly the same: the US gets to use the naval base at Rota and the air base at Morón de la Frontera, in southern Andalusia, and Spain gets to say the bases are under Spanish sovereignty.^[9]

Here is the relevant language: US aircraft "may overfly, enter and exit Spanish airspace, and use the bases specified in the Agreement with no other requirement than compliance with Spanish air traffic regulations." For anything beyond that — any use not contemplated by the agreement, or inconsistent with international law as Spain interprets it — Madrid has to authorize it.

If you were structuring this as a contract, it's a permissive-use license with a sovereignty carve-out. The US has broad operational access. Spain retains a veto. For seventy-three years, the veto was mostly decorative. Now it isn't.

What happened

On Saturday, the US and Israel launched strikes against Iran. On Sunday, the Spanish government told Washington that Rota and Morón could not be used to support those operations — not for staging, not for refueling, not for anything connected to the strikes.^[1]

Fifteen US aircraft — primarily Boeing KC-135 Stratotanker aerial refueling planes — left the two bases over the following 48 hours. Nine tankers flew from Morón to Ramstein Air Base in Germany. Others departed Rota toward southern France. The US military simply relocated its refueling capacity north.^[4]

The operational disruption, in other words, was minor. The political disruption was not.

The trade threat

President Trump, speaking beside German Chancellor Friedrich Merz on Monday, said: "We're going to cut off all trade with Spain." He added: "In fact, I told Scott to cut off all dealings with Spain" — referring to Treasury Secretary Scott Bessent. He also repeated his criticism of Spain's defense spending.^[7]

Some context on what "cutting off all trade" would mean in practice.

US-Spain bilateral goods trade in 2025 was roughly $47 billion — $26.1 billion in US exports, $21.3 billion in Spanish imports — with a US surplus of $4.8 billion.^[10] That's not nothing, but it's not Mexico either. More importantly, the EU negotiates trade agreements collectively. The US cannot unilaterally impose a bilateral embargo on Spain without effectively picking a fight with the entire European Union.

Treasury Secretary Bessent clarified that the US Trade Representative and Commerce Department would "begin investigations and we'll move forward with those." Which sounds less like an embargo and more like a bureaucratic process that takes months.

One way to read this is: it's a genuine threat, and Spain should be worried. Another way is: it's a negotiating tactic aimed at a domestic audience, and the structural constraints on actually cutting off trade with a single EU member state make it largely performative. In any case, the IBEX 35 dropped 0.93% at the open, Spanish bond spreads over German bunds widened to 47 basis points — the highest since December — and shares of Santander and BBVA fell 1-2%.^[8] Then the market reversed by midday. Make of that what you will.

The "agreed to cooperate" incident

On Wednesday, White House Press Secretary Karoline Leavitt told reporters: "With respect to Spain, I think they heard the president's message yesterday loud and clear, and it's my understanding, over the past several hours, they've agreed to cooperate with the US military."^[5]

Moments later, Spanish Foreign Minister José Manuel Albares went on Cadena SER radio and said: "I categorically deny any change... our position on the use of the bases, on the war in the Middle East, on the bombardment of Iran, has not changed at all."

Sánchez himself, in a press conference later that day, summarized his government's position in four words: "No to the war."^[2]

So either the White House and Madrid have different definitions of "cooperate," or someone was saying something that wasn't true for tactical reasons. I don't know which. Both interpretations are consistent with the incentives.

The defense spending problem

The base dispute is layered on top of a longer-running structural disagreement about money.

NATO's original defense spending target was 2% of GDP, set in 2014. Most members didn't meet it for years. Spain was among the worst offenders — spending around 1.28% of GDP in 2024, the lowest proportion among all 32 allies.^[11] In 2025, Madrid made a large jump, reaching roughly 2% for the first time, via a 43% year-over-year increase to €33 billion.

Then, in June 2025, under US pressure, NATO adopted a new target: 5% of GDP by 2035, with 3.5% for core military and 1.5% for related spending like cyber and infrastructure. Spain was the only member that refused to commit. Sánchez wrote to NATO Secretary-General Mark Rutte calling the 5% figure "unreasonable" and "counterproductive," warning it would gut Spain's welfare state.^[12]

He negotiated a special exemption: Spain would cap at 2.1% of GDP, described as "sufficient and realistic."^[6]

The incentive ladder here is fairly clear:

1. The US wants allies to spend more on defense, partly because it wants burden-sharing, partly because higher European defense budgets flow substantially into US defense contractors.
2. NATO sets a target. Most members nod along.
3. Spain says no, because Sánchez runs a fragile minority coalition that depends on left-wing and regionalist parties who view military spending as money taken from social programs.
4. Spain negotiates a carve-out.
5. The US resents the carve-out but can't force compliance, because NATO targets are voluntary.
6. When a real crisis arrives — Iran — the resentment becomes leverage, and the leverage gets stapled onto the trade threat.

So the base dispute and the spending dispute are now a single dispute. Convenient, if you're Washington.

The coalition math

It helps to understand why Sánchez does what he does. He leads a minority government. The PSOE and its junior coalition partner Sumar hold about 155 of 350 seats in Congress. To govern, they rely on a patchwork of support from ERC (Catalan republicans), Junts (Catalan independentists), EH Bildu (Basque left-nationalists), PNV (Basque centrists), and a handful of smaller parties.

This coalition has suffered over 100 parliamentary defeats since taking office. Junts has periodically withdrawn support. The whole thing is held together less by ideology than by the fact that nobody can assemble a majority to replace it.

The coalition partners — especially Sumar and the remnants of Podemos — have been pushing Sánchez leftward on foreign policy for years. Spain recognized Palestine in May 2024. It supported South Africa's ICJ case against Israel. It suspended arms exports to Israel. And now, blocking US bases for an Iran operation is the logical extension of a trajectory that was already locked in by domestic coalition dynamics.

If you were Sánchez, the mechanism is straightforward: allow the bases to be used, and your coalition collapses. Block them, and you face Trump's anger but keep your government. The domestic risk is immediate and existential; the foreign risk is large but diffuse and shared with the EU.

Of course.

The structural bug

Here's the part that makes this interesting rather than just noisy.

The 1953 framework was designed for the Cold War. The US needed bases in southern Europe to project power toward the Soviet Union and the Mediterranean. Spain needed economic aid and international legitimacy (it was, again, a dictatorship). The deal worked because the interests were aligned and the sovereignty veto was never tested against a real disagreement.

The bug is that the agreement survived the transition to democracy, survived the end of the Cold War, survived Spain joining NATO in 1982, and survived multiple renewals — all without anyone seriously renegotiating the veto mechanism for a scenario in which the host country's government was ideologically opposed to the operation being staged from its territory.

The US assumed the veto would remain decorative. Spain assumed the alliance would never require it to be complicit in something its electorate opposed. Both assumptions were correct until this week.

Now the question is whether the agreement gets renegotiated, or whether the US simply routes around Spain — which it already did, operationally, by moving the tankers to Ramstein in 48 hours. If the workaround is that easy, the agreement loses leverage for both sides: Spain can't offer basing rights as a contribution if the US doesn't need them, and the US can't threaten to leave if it already has alternatives.

The trade plumbing

One more thing on the trade threat, because the mechanics matter.

EU trade policy is a shared competence under Article 207 of the Treaty on the Functioning of the European Union. The European Commission negotiates trade agreements on behalf of all 27 member states. The US cannot impose a bilateral tariff on Spain alone without either (a) imposing it on all EU imports of the same product, or (b) inventing a novel legal mechanism that targets a single member state within a customs union.

Option (a) is a much bigger fight than Trump-vs-Spain. Option (b) doesn't exist in current WTO or bilateral frameworks.

What the US can do: targeted sanctions on individuals, restrictions on specific defense or technology transfers, regulatory harassment of Spanish firms operating in the US. Treasury Secretary Bessent's mention of "investigations" points in this direction. But "cut off all trade" is not a thing that can happen to one EU member state without happening to all of them.

The European Commission seems to understand this. Spokesperson Olof Gill said: "We stand in full solidarity with all member states and, through our common trade policy, stand ready to act if necessary to safeguard EU interests."

In other words: go ahead, but you'll be negotiating with Brussels, not Madrid. Unsatisfying, if you're Washington.

What this is actually about

A running theme here is:

1. A Cold War-era basing agreement creates mutual obligations.
2. The obligations are vague enough that both sides read them differently.
3. A crisis forces a test of the ambiguity.
4. The test reveals that the agreement doesn't do what the more powerful party assumed it did.
5. The more powerful party responds with economic threats.
6. The economic threats are structurally constrained by a third-party framework (the EU) that nobody factored into the original bilateral deal.
7. Everyone acts surprised.

The base dispute will likely resolve quietly — the US has already moved its aircraft, Spain has already made its point, and neither side benefits from prolonged escalation. The defense spending dispute will persist, because the incentives haven't changed. And the broader question — whether NATO's southern European members can be relied upon for operations outside the traditional Euro-Atlantic theater — is one that the alliance has been avoiding for decades.

Spain has just made it harder to avoid.

---

Things happen

Spain's economy grew 3.2% in 2025, the fastest in the eurozone. The BBVA-Sabadell takeover bid failed in October after only 25% of shareholders tendered. Banco Santander is buying TSB from Sabadell for £2.9 billion. The European Council held an emergency session on the Iran strikes. Turkey also refused US basing requests. The UK initially declined, then reversed course. Germany accepted the relocated tankers without public comment. Spain's next scheduled general election is in 2027, but nobody expects the coalition to last that long.