In a letter sent to Rumsfeld on Tuesday, People for the Ethical Treatment of Animals contends that the troops deserve the best defense but that using animals this way is cruel and may cost lives instead of saving them.
The request follows reports that a 33-year-old dolphin, named Takoma who was charged with hunting for mines in the Iraqi port of Umm Qasr, went missing for more than 48 hours.
While dolphins are highly intelligent animals, they do not understand that lives depend on their assignments and they can be easily distracted from their missions, according to PETA.
The Pentagon recently announced that the U.S. Navy is using dolphins and sea lions to intercept terrorists and mines in the Persian Gulf. The U.S. Army and the Marines are using chickens and pigeons to detect biological and chemical weapons and dogs to detect weapons and rescue troops.
Messages left with the Navy seeking comment were not returned.
In her letter to Rumsfeld, PETA wildlife caseworker Stephanie Boyles also expressed concern over the use of chickens and pigeons in Kuwait, dozens of whom have died. The birds were sent to detect poison gas even though units stationed in the region have already been outfitted with chemical detection equipment.
"Wars are human endeavors," wrote Boyles. "While a person, a political party, or a nation may decide that war is necessary, the animals never do. Like civilians, they often become the victims of war, but now the U.S. military is deliberately putting animals in harm's way."
"These animals never enlisted," the letter continues. "They know nothing of Iraq or Saddam Hussein, and there is also no guarantee that these animals will save human lives. In fact, they may cause the loss of lives."
Based in Norfolk, Va., PETA claims more than 750,000 members and supporters worldwide.