WASHINGTON, May 19 (UPI) -- The newest threat to U.S. national security is animal rights and environmental groups, senior law enforcement agencies told the U.S. Senate. In testimony before the Senate Environment Committee Wednesday, officials from the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives identified three groups of concern -- the Animal Liberation Front, the Earth Liberation Front and People for the Ethical Treatment of Animals, CNN reported Thursday. John Lewis, the FBI's deputy assistant director for counterterrorism, said various animal and environmental rights extremists have claimed responsibility for more than 1,200 criminal incidents since 1990, and...