Nearly half a century after a midair plane collision sent U.S. nuclear bombs tumbling down onto the Spanish countryside, the two governments are still trying to clean up the radioactive mess the accident left behind.
Two American military aircraft, a B-52 bomber and a KC-135 refueling plane, crashed into each other above the rural village of Palomares in southeastern Spain on January 17, 1966.
Three nuclear bombs hit the ground, and the other fell into the Mediterranean.
None of them set off a nuclear detonation, but two of them spewed plutonium over the surrounding area.
The disaster has been ranked as one of the worst nuclear disasters of the Cold War that highlighted the dangers of the arms race between Washington and Moscow. And it has proved to have a long legacy.
During a visit to Madrid on October 19, 2015, U.S. Secretary of State John Kerry signed a new document pledging further assistance in the decade-long cleanup, including the likely disposal of contaminated soil in America.