Testimony by a number of congressional leaders supports the legislation, as they argue that terrorists could take plastic firearms through existing airport security undetected. They also indicate that the legislation does not hamper the advancement of firearms technology, since even predominantly plastic weapons could contain identifiable, detectable metal parts that would not seriously compromise firearms design. A representative of the Bureau of Alcohol, Tobacco, and Firearms argues that existing detection devices can detect any currently manufactured firearms and that existing law requires a metallic plate for firearms identification information. A spokesperson for the Office of Technology Assessment indicates the current firearms technology can produce an all-plastic gun which existing surveillance technology cannot detect. Other witnesses, including representatives of firearms associations, oppose the bills, arguing that the emphasis should be on upgrading detection systems, since the weapons targeted by the legislation could be purchased outside the United States. They also view the legislation as an undue obstruction to advancement in firearms technology.