Italy refused to allow the United States to use the Sigonella air base in Sicily for strikes on Iran, but attempted to keep the decision secret to avoid a diplomatic rift with Washington, Corriere della Sera reported on March 31.

The Italian defence minister denied the request after Rome learned that two US F-15 fighter jets planned to use the base while already airborne on a combat mission against Iran, La Sicilia reported.

Washington had not sought prior permission or consulted Italian military leadership, instead informing Rome only after the aircraft were in flight.

"No one requested authorisation or consulted with Italian military leadership. The plan was communicated to Rome when the aircraft were already in flight," Corriere della Sera reported, noting that the US had intended to use the base on a notification-only basis.

The use of Italian military bases for attacks on other countries contravenes bilateral agreements between Rome and Washington, the newspaper said. Sigonella currently hosts US P-8A Poseidon patrol aircraft, MQ-4C Triton and RQ-4D Phoenix drones operating under NATO tasks.

Italian Prime Minister Giorgia Meloni reportedly sought to keep the refusal quiet to avoid damaging her relationship with the Trump administration. The issue was politically sensitive: almost 25,000 people marched in Rome under the "No Kings" banner two days earlier in protests against the war in Iran, with similar rallies held in London, Paris and Madrid, TASS reported.

Italy is the second European NATO ally to deny the US use of its bases for the Iran war. Spain's Prime Minister Pedro Sanchez publicly refused access to two Spanish bases, saying his country would not participate in what he called an illegal war.

US Secretary of State Marco Rubio expressed frustration at Madrid's decision, with some in Washington calling for sanctions against Spain.

The growing European resistance to the war highlights the diplomatic strain the conflict is placing on the transatlantic alliance, with virtually all major US allies in Europe declining to provide direct military support for operations against Iran.