The US Navy has agreed to stop its funding of medical testing on sheep at the University of Wisconsin-Madison following action by an animal rights group.
People for the Ethical Treatment of Animals (PETA) says their campaign of letter writing, protests and legal action has put an end to a series of experiments that were designed to study ways of rescuing sailors trapped in sunken submarines.
The sheep were subjected to the simulated conditions of surfacing quickly from a great depth, causing the animals pain and sometimes leaving them paralysed or dead, according to Shalin Gala, vice president at PETA.
Mr Gala told Military.com in January: "These tests are scientifically worthless and fall far short of international standards."
He described the decompression and oxygen toxicity experiments as "gruesome" and "useless".
The research mainly focused around using hyperbaric chambers to investigate decompression sickness, causing nitrogen bubbles to form in the sheep's blood.
The condition is commonly known as "the bends" and can be deadly for divers.
The UK ended the use of live goats for hyperbaric research in support of the Ministry of Defence's Submarine Escape Rescue and Abandonment System (SMERAS) in 2008.