WWW- After all the thousands of AIDS deaths and all the years of “Safe Sex Is Hot Sex” prevention messages, it has come down to this: many gay men who know the rules of engagement in the age of AIDS are not using condoms. As news of a potentially virulent strain of H.I.V. settles in, gay activists and AIDS prevention workers say they are dismayed and angry that the 25-year-old battle against the disease might have to begin all over again.

While many are calling for a renewed commitment to prevention efforts and free condoms, some veterans of the war on AIDS are advocating an entirely new approach to the spread of unsafe sex, much of which is fueled by a surge in methamphetamine abuse. They want to track down those who knowingly engage in risky behavior and try to stop them before they can infect others.

It is a radical idea, born of desperation, that has been gaining ground in recent months as a growing number of gay men become infected despite warnings about unsafe sex.

Although gay advocates and health care workers are just beginning to talk about how this might be done, it could involve showing up at places where impromptu sex parties happen and confronting the participants. Or it might mean infiltrating Web sites that promote gay hookups and thwarting liaisons involving crystal meth.

Other ideas include collaborating with health officials in tracking down the partners of those newly infected with H.I.V. At the very least, these advocates say, gay men must start taking responsibility for their own, before a resurgent epidemic draws government officials who could use even more aggressive tactics.

“Gay men do not have the right to spread a debilitating and often fatal disease,” said Charles Kaiser, a historian and author of “The Gay Metropolis.” “A person who is H.I.V.-positive has no more right to unprotected intercourse than he has the right to put a bullet through another person’s head,” he said.

While not endorsing specific strategies, even mainstream organizations like the Gay Men’s Health Crisis support the idea of trying methods that would have been anathema a few years ago. “It makes a community stronger when we take care of ourselves,” said Ana Oliveira, the organization’s executive director, “and if that means that we have to be much more present and intervene with people who are doing this to themselves and others, then so be it.”

For many others, however, even talk of such steps provokes hand-wringing. “We don’t want public health vigilantes going out and taking matters into their own hands, particularly if it means breaching the confidentially and civil rights of people with H.I.V.,” said Jon Givner, the director of the H.I.V. Project at the Lambda Legal Defense and Education Fund. “Frankly, I find it pretty scary.”

Whether such ideas gain acceptance, the fact that activists are even thinking about curbing gay sexual freedom is a huge shift.

In the early years of the AIDS epidemic, gay men protested attempts to close down bathhouses and strenuously opposed efforts by health officials to trace those infected with the virus. Until now, those advocates, driven by concerns about privacy and the stigma associated with the disease, have successfully fought off efforts to impose a traditional public-health model for tackling the spread of the virus.

“You have to remember that was the era when Jesse Helms and others were saying that gay people got what they deserved, and that the government shouldn’t spend any money to help them,” said David Evans, an H.I.V. treatment advocate who writes about prevention. “There was a time when people thought, ‘Oh my god, they’re going to put us in camps.’ ”

Such fears have faded in recent years, thanks in part to laws that protect people with AIDS against discrimination. Although the number of AIDS-related deaths has plummeted since the advent of a more potent class of drugs in the mid-90’s, the rate of new infections has remained unchanged at about 40,000 cases a year, frustrating many advocates.

That frustration has been ratcheted up by the growing popularity of crystal meth in New York, which many say has led to an abrupt increase in unsafe behavior and a spate of infections. Although exact figures are difficult to determine, a recent survey of gay men found that 25 percent had tried crystal meth in the last few months.

Those frustrations were given voice in November by Larry Kramer, the playwright and activist who himself has AIDS, in a widely discussed speech at Cooper Union in which he criticized gay men for their behavior. “You are still murdering each other,” he said then. “Please stop with all the generalizations and avoidance excuses gays have used since the beginning to ditch this responsibility for this fact.”

In an interview, Mr. Kramer said on Sunday that the warning of a possibly aggressive new strain of H.I.V. confirmed his fears and filled him with a sense of hopelessness. “Even in the days of the worst infections, no amount of prevention seemed to work, and that’s probably the scariest thing of all,” he said.

Even if the warning turns out to be a false alarm, many AIDS experts say it is only a matter of time before a supervirus does emerge.

“You can’t have a core group of people having sex with large numbers of people without amplifying any sexually transmitted disease that enters the system,” said Gabriel Rotello, author of “Sexual Ecology: AIDS and the Destiny of Gay Men.” “I don’t have any doubt that a resurgent H.I.V. epidemic will hit the gay population in the near future,” he said.

It is this fear of a drug-resistant virus that has driven some who track the spread of AIDS to suggest a more aggressive approach to prevention. Walter Armstrong, the editor in chief of Poz, a monthly magazine about AIDS and H.I.V., said the traditional fear-based approach to prevention was at best only a temporary solution, especially if no supervirus outbreak materializes. A more effective approach, he said, would involve gay organizations using traditional public health measures, such as more widespread screening and a partner-notification effort to track users of crystal meth who have been infected recently.

“Why would it not be possible to get them together to communicate to each other, and then to their sex partners, that lives are being put at risk by reckless behavior?” he asked. “I think there are ways to do interventions ethically, sensitively and compassionately. There’s a huge window of opportunity between criminalization and empty prevention messages.”

Still, others remain wary of such measures. Walt Odets, a clinical psychologist and the author of “In the Shadow of the Epidemic: Being HIV-Negative in the Age of AIDS,” said he thought such intervention smacked of a witch hunt.

He and others said it would be more effective to try to identify the underlying causes of drug abuse and self-destructive behavior, including the difficulty of living in a society that rejects committed gay relationships while condemning homosexuals for having sex outside those relationships. Gay men, he said, are using methamphetamines as an anti-depressant.

Many health experts suggest a more vigorous return to conventional H.I.V. prevention. Isaac Weisfuse, the city’s deputy commissioner of health, said his agency was planning to place information banners on gay Web sites and devote more money to hard-hitting ads about methamphetamine use.

And, he noted, the free condom has largely disappeared from public places. “Unfortunately, condom use has fallen off the radar screen,” he said. “We need to do something we did well 20 years ago, which is to get condoms in every place people socialize or have sex.”

Others, like Mr. Rotello, were less optimistic. Until people really believe an unstoppable virus is out there, he said, they will continue to indulge in unsafe sexual practices. “People are not going to modify their sexual habits in ways that are difficult or unpleasant until they see their friends dying again,” he said. “And to me that’s just an unbelievably depressing thought.”