Almost 50 years after four nuclear bombs fell on the Spanish coast after two US military planes collided, American officials have signed a deal to clean up contaminated land.
None of the bombs detonated in January 1966, but three fell around Palomares and a fourth was found on the sea bed.
Highly toxic plutonium was spread over a 200-hectare (490-acre) area.
On a visit to Madrid, Secretary of State John Kerry agreed to finalise a deal on disposing of contaminated soil.
Under the agreement in principle, signed by Mr Kerry and Spanish Foreign Minister Jose Manuel Garcia-Margallo, the US will remove the soil at Palomares to a site in the US.
Spanish media said the soil would be transported to a site in Nevada. The deal comes a few months before the 50th anniversary of the crash, one of the most serious nuclear incidents of the Cold War.
An earlier consignment of contaminated soil was shipped to a site in South Carolina shortly after the accident and buried in deep trenches.
But further analysis of soil in the area has been carried out in recent years, and the health of residents in the Palomares area is still being monitored.