U.S. President Donald Trump said Friday he's delaying a new policy allowing the body parts of African elephants shot for sport to be imported until he can review "all conservation facts."

The U.S. Fish and Wildlife Service said Thursday that it will allow the importation of body parts from African elephants shot for sport. The agency said encouraging wealthy big-game hunters to kill the threatened species would help raise money for conservation programs.

Animal rights advocates and environmental groups criticized the decision. On Friday, the Republican chairman of the House foreign affairs committee urged the administration to reverse the policy, calling it the "wrong move at the wrong time."

California Rep. Ed Royce questioned the action because of concerns not only about African wildlife but U.S. national security, citing the political upheaval in Zimbabwe, where the longtime president was placed under house arrest this week by the military.

"The administration should withdraw this decision until Zimbabwe stabilizes," the committee chairman said in a statement. "Elephants and other big game in Africa are blood currency for terrorist organizations, and they are being killed at an alarming rate. Stopping poaching isn't just about saving the world's most majestic animals for the future — it's about our national security."

Trump tweeted Friday that the policy had been "under study for years." He said he will review the issue with Interior Secretary Ryan Zinke.

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A herd of elephants walk past a watering hole in Hwange National Park October 14, 2014. The watering hole was one of several that were contaminated by poachers with cyanide in 2013, leading to the death of at least 100 animals, according to Zimbabwean authorities. (Philimon Bulawayo/Reuters)

The Fish and Wildlife Service said in a written notice issued Thursday that permitting elephants from Zimbabwe and Zambia to be brought back as trophies will raise money for conservation programs. The change marks a shift in efforts to stop the importation of elephant tusks and hides, overriding a 2014 ban imposed by the Obama administration. The new policy applies to the remains of African elephants killed between January 2016 and December 2018.

"Legal, well-regulated sport hunting as part of a sound management program can benefit certain species by providing incentives to local communities to conserve those species and by putting much-needed revenue back into conservation," the agency said in a statement.

Royce said that when carefully regulated, conservation hunts could help the wildlife population, but "that said, this is the wrong move at the wrong time."

He described the perilous situation in Zimbabwe, where the U.S. Embassy has advised Americans to limit their travel outdoors.

Threatened since 1979

"In this moment of turmoil, I have zero confidence that the regime — which for years has promoted corruption at the highest levels — is properly managing and regulating conservation programs," Royce said. "Furthermore, I am not convinced that elephant populations in the area warrant over-concentration measures."

'We should not encourage the hunting and slaughter of these magnificent creatures.' —  Rep. Vern Buchanan

The world's largest land mammal, the African elephant has been classified as threatened under the U.S. Endangered Species Act since 1979.

Illicit demand for elephant ivory has led to devastating losses from illegal poaching as the natural habitat available for the animals to roam has also dwindled by more than half. As a result, the number of African elephants has shrunk from about 5 million a century ago to about 400,000 remaining. And that number continues to decline each year.

Two other lawmakers, Reps. Vern Buchanan, a Florida Republican., and Earl Blumenauer, a Democrat from Oregon, co-chairs of the Congressional Animal Protection Caucus, criticized the administration's decision.

"We should not encourage the hunting and slaughter of these magnificent creatures," Buchanan said. "We don't get a second chance once a species becomes extinct."