Just days from telling her story to the Waco hearings, Attorney General Janet Reno on Thursday defended her decision to order a tear-gas raid that ended the siege at the Branch Davidian compound. "I don't know any other way I would have approached it," she said.

Reno addressed reporters at her weekly news conference as the FBI agents who advised her during the Waco siege were being grilled by two House subcommittees at the hearings. Reno is scheduled to testify Monday.A fire broke out during the FBI assault, and 81 bodies were found in the ashes later. Reno said she has reviewed her decision "again and again" and - based on the information she had two years ago - doesn't believe she could have made a different decision.

"It is the most difficult decision that I have ever made and one that I live with regularly," Reno said. "Nobody will ever know what the right answer was."

Before Reno made the decision, "there were extensive internal discussions that went on for several weeks," the FBI's former deputy director, Larry Potts, told lawmakers Thursday.

"We believe it to be the absolutely least harmful of any" of the types of tear gas, Potts testified, referring to the CS gas used at Waco. He said Reno first determined that "it would not be harmful to the children . . . but it would drive them out of the house."

Potts said Reno wanted specific rules of engagement for the Waco operation, "to make sure that we go out of our way not to gas the children."

Harry Salem, a civilian Army expert who advised Reno before her decision, called CS gas "the safest and most potent riot control agent that we know of."

Potts was removed July 14 because of controversy over his role in a deadly 1992 FBI siege in Idaho. He managed that operation and the Waco siege from FBI headquarters while he was an assistant director.

Reno said that as a result of that disaster she has expanded the size of the FBI Hostage Rescue Team and could now send in a new team if the same situation arose again. One argument for ending the siege was that the team had been in place so long it was exhausted.

But she dismissed critics who said she was inadequately informed about the potential dangers of the CS gas used in the raid or was pressured into her actions by President Clinton or by the FBI.

As for the gas, she said, "I asked the questions: What about children, what effect would it have? The FBI consulted with Dr. Harry Salem, who I was advised was the foremost toxicologist having information with respect to the effects of CS gas, and I was told that it would not be permanently injurious."

As she has from the day of the assault, April 19, 1993, Reno took full responsibility for the decision.

"The president of the United States never pressured me to do anything in this matter," she said.

Despite suggestions to the contrary by others, Reno said, "I still see no indication whatsoever that the FBI misled me or in any way pressured me. In fact, the FBI, every time I raised a question, tried to respond with solid information, tried to provide people like Dr. Salem to answer my questions. When I asked about the water supply, instead of just . . . giving me a summary conclusion, they went back and checked it out."

Reno said she faced these options: "I could have gone in with a frontal assault, which could have been extraordinarily dangerous to all concerned, and we knew that upfront. I could have waited, and I won't know - and will never know - what (cult leader) David Koresh might have done six days later or six months later or six years later.

"I continue to try to think of what I would do, review it again and again," she said.