The justices offer no comment on their action Monday, rejecting appeals in three separate cases, in favor of Dow Chemical, Monsanto and other companies that made Agent Orange and other herbicides used by the military in Vietnam.

Agent Orange has been linked to cancer, diabetes and birth defects among Vietnamese soldiers and civilians and American veterans.

The American plaintiffs blame their cancer on exposure to Agent Orange during the military service in Vietnam. The Vietnamese said the U.S.' sustained program to prevent the enemy from using vegetation for cover and sustenance caused miscarriages, birth defects, breast cancer, ovarian tumors, lung cancer, Hodgkin's disease and prostate tumors.

All three cases had been dismissed by the 2nd U.S. Circuit Court of Appeals in New York.

The appeals court said that lawsuit brought by the Vietnamese plaintiffs could not go forward because Agent Orange was used to protect U.S. troops against ambush and not as a weapon of war against human populations.

The other two suits were filed by U.S. veterans who got sick too late to claim a piece of the $180 million settlement with makers of the chemical in 1984. In 2006, the Supreme Court deadlocked 4-4 on whether those lawsuits could proceed.