Animal rights advocates denounced the Trump administration's reversal of a ban on animal trophy imports, announced in a memo issued last week, and the secrecy with which President Donald Trump's U.S. Fish and Wildlife Service (USFWS) will now allow some Americans to import endangered species they have killed in African countries.

The agency said it would begin issuing permits "to import a sport-hunted trophy on a case-by-case basis," effective immediately, but did not share what guidelines it would follow in making those decisions.

The Center for Biological Diversity objected to the lack of transparency as well as the Trump administration's refusal to protect elephants, lions, and other animals in African countries including Zimbabwe, Zambia, and Botswana.

Their decision-making on elephant trophy imports needs to be in the public, not behind closed doors. And quite simply, elephants in the wild need to roam freely, and unencumbered from trophy hunts, ivory poaching, and the illegal trade that is driving their numbers downward. pic.twitter.com/DFUojX93SE — Center for Bio Div (@CenterForBioDiv) March 6, 2018

The decision comes four months after President Donald Trump announced he would reinstate a 2014 ban on animal trophy imports, calling trophy-hunting a "horror show" despite the abundance of evidence that his sons have hunted animals and posed proudly with their "trophies."

The president announced the ban last November after the public outcry that ensued when he briefly reversed President Barack Obama's directive outlawing trophy imports.

"We saw the public outcry last fall when [the trophy decision] was announced…not just from people who are traditionally Democrats," Tanya Sanerib, an attorney with the Center for Biological Diversity, told the Huffington Post on Tuesday. "The agency is really playing hide the ball. It's incredibly disappointing."

In December, a federal appeals court ruled in favor of the National Rifle Association (NRA) and Safari International, which had sued the Obama-run USFWS on the grounds that the 2014 trophy ban was implemented without a public comment period, among other complaints. The decision to permit trophies on a case-by-case basis was made by the USFWS in light of the appeals court's decision.

But on social media, some accused the Trump administration of sneakily reversing its earlier decision while Americans' attention is focused elsewhere, months after the animal trophy uproar.