Transcript for American man tries to save rhinoceroses in South Africa

Next this evening, to south Africa, where on average three white rye no, sirlesses are killed every day, by poachers who want to get to those valuable horns. Tonight, the american-based group trying to help save them, with a very unusual and controversial approach. ABC's Bob woodruff from south Africa. Reporter: National parks in South Africa are under siege. All for this. Worth over $300,000 on the black market, it's a brutal trade. But with rhino horn demand at an all-time high, and criminal and terror groups profiting off the sale, rhinos not under lock and key are rapidly being poached into extinction. The way we look at it is, one single horn on the black market can buy as many as 1,000 ak-47 rifles. One single horn can keep 75 ISIS fighters in kit and armaments for 12 months. Reporter: But there might be some hope. This is rhino 911, a nonprofit co-founded by Fred hees, based in Nevada. They're working around the clock to protect rhinos and other wildlife. Veterinarian gerardhus sheepers, darting the rhinos from the air. The horns are cut and sanded, leaving behind only a couple of inches, so it can regrow. Providing an inexhaustible supply of a commodity more valuable than gold. Coveted for their supposed medicinal value. The debate has reached a boiling point. On the potential lifting of the controversial ban that would make it legal to sell rhino horn internationally. Whether we like it or not, we have to dehorn these rhino. I fought that decision for about five years, and that cost us five rhino. And I will never get over it. And Bob woodruff will have much more on how they do this, using infrared cameras to spot the poachers. And Bob's report from south Africa continues tonight,that's on "Nightline" right after Jimmy Kimmel. When we come back tonight,

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