The world’s most powerful animal protection law has designated two subspecies of African lions as threatened or endangered species, offering them legal protection that will make it harder for hunters to import lion trophies into the U.S., BusinessInsider reported.

The U.S. Fish & Wildlife Service on Monday listed lions found mostly in West and Central Africa under the Endangered Species Act and lions in Eastern and Southern Africa as “threatened.”

About two thirds of trophy hunters are Americans, conservationists say. Violators will have permits withheld, according to the report.

Only about 1,400 of the lions designated as endangered are left  in West and Central Africa, according to BusinessInsider.

Protection for the lions will become effective January 2016. African elephants and cheetahs have been protected under the same act.

Populations of the two lion subspecies have been decimated by loss of habitat and the food they prey upon, by local communities, and hunters, BusinessInsider reported.

Several African countries still allow tourists to hunt their lions for sport and trophies, saying it provides an important source of revenue and helps support conservation.

These include South Africa, Zimbabwe, Botswana, Zambia, Namibia and Mozambique , TheGuardian reported in July.

Lions are extinct in the Congo, Cote d’Ivoire, Ghana, and Nigeria, according to a 2011 report by LionAid.

The trophy hunting debate made world headlines after U.S.  dentist Walter Palmer killed Cecil, a rare and beloved black-maned lion in Zimbabwe. Hunters like Palmer regularly import salt-packed lion skulls and skins into the U.S., BusinessInsider reported.

The U.S. Fish & Wildlife Service condemned Cecil’s killing but denied that the new measures were linked to it.

Many conservationists say that without trophy hunting there would be no lions at all, TheGuardian reported.

“The land would be used for farming and this would accelerate the loss of wildlife. We don’t like trophy hunting but it slows the rapid decline of populations. It is a necessary evil,” said Guy Balme, director of the leopard program in Africa for U.S.-based conservation group Panthera.

Imports of a rare subspecies found in west and central Africa and India will be “generally prohibited” under the new measures, the agency said, unless licencees can show they enhance the survival of the species.

Hunters will need permits to bring back trophies of lions found in other parts of Africa, and only from countries “with established conservation programs and well-managed lion populations,” the agency said, according to BusinessInsider.

France said in November it will stop issuing permits to import trophy lions. Australia has passed a similar act.