Korean and American veterans who served in the late 1960s filed a class action suit in U.S. District Court in Philadelphia on Friday against the makers of three defoliants — Agent Orange, Agent Blue and Monuron — claiming the chemicals have had delayed toxic effects on the soldiers exposed to them.

Attorneys Stewart J. Eisenberg of Weinstein Goss Schleifer Eisenberg Winkler & Rothweiler and Michael Choi of Choi & Associates filed the suit against six defendants — Dow Chemical Co., Occidental Electro-Chemical Corp., Hercules Inc., Monsanto Co., Uniroyal Inc. and Thompson Hayward Agriculture & Nutrition Inc.