Washington ratcheted up pressure on Venezuela's leftist President Nicolas Maduro on Thursday with new measures aimed at disrupting the South American country's gold exports, U.S. national security adviser John Bolton said.

Bolton promised a tough stance by the Trump administration toward "dictators and despots near our shores" and singled out Venezuela, Cuba and Nicaragua in a speech in Miami, which is home to large numbers of migrants from Cuba and Venezuela.

He spoke days before U.S. elections next week that include close races for a Senate seat and the governorship in Florida. His remarks were likely to be well received by those Cuban-Americans and other Hispanics in Florida who favor stronger U.S. pressure on Cuba's Communist government and other leftist governments in Latin America.