Which european power was the first to begin importing slaves to its colonies in the americans?

The Transatlantic Slave Trade started shortly after the year 1500. The first documented case of slavery dates back to  Juan de Córdoba, a Spaniard, who brought one African Slave to the Americas with the permission of his Spanish Crown. The first country to send slaves to the Americas seems to be thus Spain, only a few years after the discovery of America.