Washington ? The military secretly tested sarin nerve agent in a Hawaii forest preserve in 1967, the Pentagon acknowledged Thursday in the latest disclosures about Cold War-era testing of biological and chemical weapons.

Other secret tests in Hawaii in 1966 and the Panama Canal Zone in 1963 released a germ meant as a harmless stand-in for the bacteria that cause anthrax, the Defense Department said. A 1966 experiment in an undisclosed “tropical jungle type environment” involved spraying tear gas on unprotected U.S. military volunteers.

The Defense Department released summaries of five chemical and biological weapons tests Thursday. The disclosures were part of an effort to research and make public such tests from the 1960s and 1970s to alert veterans who may have been exposed.

The tests were part of Project 112, a military program in the 1960s and 1970s to test chemical and biological weapons and defenses against them. Parts of the testing program done on Navy ships were called Project SHAD, or Shipboard Hazard and Defense.

The United States scrapped its biological and chemical weapons programs in the early 1970s.

Some of those involved in the tests say they now suffer health problems linked to their exposure to dangerous chemicals and germs. They are pressing the Veterans Affairs Department to compensate them.

The Pentagon this year acknowledged for the first time that some of the 1960s tests used real chemical and biological weapons, not just benign stand-ins.

The Defense Department has identified about 5,000 service members involved in tests at sea and an additional 2,100 involved in the tests on land, Dr. Jonathan Perlin of the Veterans Affairs Department said this month. He said 53 veterans had filed health claims for their exposure during the tests. The agency has sent letters to 1,400 veterans involved in the tests at sea, Perlin said.

The test using sarin in Hawaii was named “Red Oak” and was conducted in April and May 1967 in the Upper Waiakea Forest Reserve on the island of Hawaii. The testers detonated sarin-filled 155 mm artillery shells to study how the nerve agent dispersed in a tropical jungle.

Sarin is the deadly nerve agent used in the 1995 terrorist attack on the Tokyo subway that killed a dozen people. Even small amounts can cause a thrashing, choking death.

The health effects of long-term exposure to low levels of sarin have not been determined, the Pentagon said.