The scene U.S. forces encountered as they entered Kuwait in February 1991 to end the Iraqi occupation was a hellish inferno, with hundreds of oil wells set ablaze by Saddam Hussein’s army to send a choking, black smoke billowing into the skies.

Now, as the troops who served in the Gulf War mark its 25th anniversary on Tuesday, they are fighting a different battle. A new report once again casts doubt on the legitimacy of Gulf War Illness, an ailment afflicting hundreds of thousands of veterans of the war.

“We were appalled at the new Institute of Medicine report, although not surprised,” James Binns, former chairman of the federal Research Advisory Committee on Gulf War Veterans’ Illnesses, told FoxNews.com.

The institute is a division of the National Academy of Sciences, Engineering and Medicine, and conducts research to serve private and governmental agencies, including by congressional commission.