The White House is banning the commercial sale of ivory within the United States.
Officials say the ban will strengthen U.S. leadership in protecting endangered elephants and rhinos.
With very few exceptions, Tuesday's action outlaws the import, export and commercial trade of ivory, and limits sport hunting of African elephants.
The U.S. also will work more closely with its global partners to fight illegal wildlife poaching and reduce demand for illegally traded wildlife.
One U.S. official tells Reuters news agency that the appropriate place to observe ivory is on live elephants and rhinoceros in their native habitat.
The illegal ivory trade continues despite a global ban in 1989.