Last week, reports emerged that the US Federal Maritime Commission may investigate whether Spain is “creating unfavorable conditions for maritime transport in U.S. foreign trade by denying certain vessels access to its ports.”

These vessels are two container ships operated by Danish company Maersk, part of the Maritime Security Program (MSP), a fleet of commercial ships available to the US Department of Defense in cases of war. The ships were denied entry to the Spanish port of Algeciras on November 8 and 14 while en route from New York, carrying weapons destined for Israel. The FMC could impose fines of up to €2.18 billion per ship and might even ban Spanish ships from entering US ports.

On May 16, the Spanish government, formed by the Socialist Party (PSOE) and its pseudo-leftist ally Sumar, announced its intention to ban ships carrying military materials for Israel from docking at Spanish ports.

Washington’s threat is a clear sign that it will not tolerate any opposition to arming of Israel for the genocide of Palestinians in Gaza. It comes after an Amnesty International report charged Israel with genocide, citing official figures of 44,580 killed and estimates as high as 186,000 in a study published by The Lancet. Amnesty argued this mass killing stems from genocidal intent, evident from leaders of the Israeli government down to individual soldiers.

Despite this, the US and other imperialist powers continue to back Israel as part of their agenda to reshape the Middle East under imperialist control.

But while US threats might suggest Madrid is blocking arms destined to Israel, the reality is that these are isolated and selective cases meant to obscure Madrid’s active cooperation in the arms trade, as well as other support for the Zionist regime. It is part of Spain’s attempt to posture as sympathetic to the Palestinians, such as by verbally recognizing a nonexistent Palestinian state.

An investigation by Progressive International and the Palestinian Youth Movement, published by ElDiario.es, revealed that from May to September at least 25 ships, carrying 13,000 tons of weaponry—including armored vehicles, engines, vehicle and aircraft parts, airplane tires, projectile bodies, and various military equipment—sailed from the US to Israel, stopping at Spain’s Algeciras port.

This report provided undeniable evidence that, despite pledges to the contrary, the PSOE-Sumar government continues to collaborate in the genocide in Gaza. The same ElDiario.es article reported that the Maersk Denver and Maersk Seletar ships, carrying weapons, were scheduled to arrive in Algeciras in the following days. Faced with this revelation, the government decided to act to avoid being exposed. On November 7, the Ministry of Foreign Affairs announced that both ships would not be allowed to dock in Spain.

Two days earlier, in a cynical move aimed at deflecting responsibility from Sumar, its deputy Enrique Santiago—also the secretary general of the Stalinist Communist Party—submitted a document to the State Prosecutor’s Office requesting measures “regarding the arrival … of two cargo ships from the United States bound for Israel, scheduled to transit through Algeciras.”

In other words, Santiago was asking the prosecutor to act against his own government in which his own party participates, with his colleagues serving as ministers. This maneuver was intended to create the illusion that Sumar was opposing the genocide when, in fact, they had done nothing in the preceding months to address the continued arrival of ships carrying weapons for Israel.

The PSOE-Sumar’s cynical posturing was further exposed when it refused to discuss in parliament the confidentiality agreement signed in 2014 by Spain’s right-wing Popular Party, then in power, with Israel’s Ministry of Defense. This agreement ensures absolute secrecy in arms deals between the two countries.

Nonetheless, information about the ships docking in Algeciras and their cargo is public and well-known. If PSOE and Sumar failed to act in previous months, it is because they share the same genocidal policy as the US government. They were only forced to act when their lies were exposed, and their complicity in Israel’s genocide became undeniable.

An investigation by Alejandro Pozo of the Centre Dèlas for Peace Studies found that the port of Algeciras has long served as a transit hub for weapons bound for Israel, well before May. Pozo also stressed that the ports of Valencia and Barcelona function as key links between New York, Norfolk and Savannah—the main US ports exporting arms to Israel—and Israel’s major ports, Haifa and Ashdod.

As with Algeciras, information about the ships and their cargo arriving in Valencia and Barcelona is public and can be accessed through the ports’ official websites. Pozo notes that the arrival of ships carrying weapons to Israel is the norm, rather than the exception.

These ports are essential to Israel’s genocide and military offensive across the Middle East, including Lebanon, Syria, Yemen, and preparations for war against Iran. Without the Mediterranean route, ships carrying weapons from the US would have to circumnavigate Africa and enter through the Red Sea—a much longer, costlier and riskier alternative, where the Houthi government of Yemen has attempted to stop the weapons trade by attacking ships.

By allowing the use of these ports, PSOE and Sumar are aligning with the US and NATO’s global strategy in their conflict against China, Russia and their allies.

This policy also would be impossible without the collaboration of the trade unions, the Sumar-linked Workers Commissions (CCOO), the social-democratic General Union of Workers (UGT) unions and the anarcho-syndicalist General Confederation of Labour.

The unions could have mobilised their members to block ships carrying weapons to Israel at Spanish ports, following the example of Greek dockworkers who, in October, prevented a container of ammunition from being loaded onto a ship bound for Haifa. Such actions were demanded by the Palestinian unions at the outset of Israel’s invasion over a year ago.

Indeed, a coordinated international action by port workers could block shipment of weapons and other resources to Israel, halting the genocide in Gaza and mobilizing workers for a broader political offensive against imperialism. However, the US and European union bureaucracies have done virtually nothing in this regard, allowing the arms trade to proceed.

In Spain, trying to conceal their collaboration with Israel and imperialism, the CCOO, UGT and CGT sent a letter to the Spanish government requesting an arms embargo on Israel and the development of a protocol for inspecting ships bound for Israel.

This was a despicable act. All these bureaucrats know perfectly well that this letter would achieve nothing. It is merely a maneuver to mask their inaction, which ultimately serves to defend the imperialist interests of Spain and NATO.

The PSOE-Sumar government, and previously the PSOE-Podemos coalition, have spent years preparing Spain for imperialist war. They have exponentially increased military spending to record levels, deployed more soldiers to NATO missions, and have not even halted the purchase of weapons from Israel.

There is significant opposition among workers to this policy. This was demonstrated last year by the announcement by 1,200 dockworkers of the Organization of Port Workers of that they would refuse to service any ships carrying war materiel to Israel.

Moral appeals to the imperialist governments will achieve nothing. Workers can only intervene to stop the genocide if they develop into a broader, international movement, building rank-and-file committees and taking control of their struggles out of the hands of the union bureaucracies. This alone can allow the working class to bring fully to bear its power against the Gaza war and genocide.

This requires waging a political struggle against NATO governments, including pseudo-left parties like Sumar in Spain, which support the Israeli war effort.