The United Nations has solicited enough countries to sign on to an agreement banning laser weapons in battle. Hungary became the 20th country to ratify a UN accord barring lasers that cause blindness. The agreement prohibits certain conventional weapons that are excessively injurious or have indiscriminate, harmful effects. The ban takes effect July 30, six months after Hungary's ratification. Members who signed the accord are obliged to take precautions not to cause blindness if they use laser systems for legitimate military purposes, such as rangefinding.