On Sunday, March 4, former Russian spy Sergei Skripal and his daughter Yulia ate lunch at an Italian restaurant in Salisbury, England, then walked around the corner to a pub. Less than two hours later, they were found on a bench, comatose.

Both Skripal, 66, and his daughter, 33, are now in extremely critical condition. Police say they were poisoned with a nerve agent; fingers are pointing to the FSB, Russia’s successor intelligence agency to the KGB. Skripal’s wife and son died in 2012 and 2017, respectively—she reportedly of natural causes, he on a holiday to St. Petersburg, from either liver failure or a car crash. He was 43. Two years ago, Skripal’s brother Valeri, a former Russian paratrooper, died of unknown causes after a sudden and dramatic weight loss.

“The truth of the matter is, there is always a danger to the defector and his family,” Chelsea Barsky-Dittrich, whose KGB sleeper-agent father, Jack, defected to the United States in 1988, told The Daily Beast. “You just cannot forget that the defector is a target.”

The rules of the game seem to have changed, said Joseph Wippl, a retired CIA operations officer who spent 30 years overseas as a member of the Agency’s clandestine service.

“The betrayal in the Skripal case may be a different kind of betrayal than during the Cold War,” Wippl said. “I think a lot of these people can be engaged in all kinds of things other than just being members of the Russian government, so it’s probably a little bit more ‘Russian Mafia à la Russia’ than necessarily just a critic of Putin and so on. But I can’t imagine that this assassination attempt didn’t take place without authority at the highest levels, with at least Putin winking.”

Such a brazen assassination attempt as the one on Sergei and Yulia Skripal hasn’t been carried out on a high-value defector or former intelligence officer inside the U.S. in modern memory. Could it happen here?

Of course it could, said one recent defector from the Russian intelligence services who now lives under an assumed identity in the United States.

“Russians can operate way easier here than Americans can operate in Russia,” he told the Daily Beast, adding that there is very little daylight between organized crime and the Kremlin these days. “It could happen at any moment, anywhere. Edward Snowden is way safer in Russia than any Russian defector can feel here.”

Yes, there are unwritten “rules” that have long existed within the intelligence community, and targeting retired operatives and their families was always off-limits.

But, said the former Russian spy, “There are no rules if you don’t want to follow them, and no one’s going to blame you if you don’t, that’s for sure. I have my life insurance ready to go,” he said. “My wife and son will be okay, that’s all I care about.”

You can fight an enemy and one day make peace, Vladimir Putin once said. A traitor, on the other hand, “must be destroyed, crushed.” Indeed, the Russian security services have always held a particular grudge against double agents, said Yelena Mitrokhina, who was married to the first secretary of the Soviet Embassy in Washington, D.C. when she defected in 1978, and Skripal did time in a Russian prison for selling secrets to MI6.

“In order to discourage other people from doing this, they go after people like that with a vengeance, truly,” she told The Daily Beast.

Mitrokhina wasn’t a professional intelligence officer, much less a double agent, but she was still in enough danger that the U.S. government changed her name to “Alexandra Costa” and helped her disappear into a network of safe houses around Washington. Although she was under close physical CIA protection, Costa was still deeply worried about being killed or kidnapped.

Costa, who was once known as the “lady in the blond wig,” after appearing on Nightline in obvious disguise, eventually settled down in Northern Virginia and remarried. Her new husband was a fellow defector named Stanislav Levchenko, a former KGB major who ran the Soviet Union’s active measures program in Japan. He had defected to the U.S. in 1979, subsequently revealing information to his handlers that crippled the KGB’s entire Japanese network. For this, Levchenko was sentenced to death in absentia for treason by a Moscow court.

“There were no people sitting in cars in front of our house, but security for defectors from the security services looks very much like the Witness Protection Program. Only, instead of the Marshal’s Service, the CIA is in charge of it and they do a decent job.”

Unlike Costa, Levchenko never legally changed his name. He has said he wasn’t afraid of being assassinated, but there was at least one known attempt by Soviet intelligence to locate and kill him. Costa personally revealed her new identity to the world in 1986 when she published her memoir, Stepping Down From the Stars: A Soviet Defector’s Story.

Although the CIA still checks in with her once in a while, Costa, who is now estranged from Levchenko, said she’s no longer worried for her safety, nor his.

“I always felt that the information Stan possessed had a finite time value, that eventually his usefulness ran out and at that point the danger to him diminished,” Costa said. “The recent defectors are probably under tighter security than us, the old guard, because we’ve been here a long time and it wouldn’t really service the Russians to do anything about us.”

That’s generally true, said retired CIA operations officer Charles Goslin. But, he added, Sergei Skripal’s value as an asset had seemingly faded, as well. An extrajudicial assassination in the West carries a tremendous risk of exposure, and the risk can far outweigh the gain if the target is not an actual intelligence threat.

To that end, retired KGB General Oleg Kalugin, who fled to the United States more than 25 years ago, insists the thought of being assassinated doesn’t weigh heavily on him anymore. (Now living openly in Maryland, Kalugin hastens to make clear that he did not defect but was granted political asylum.)

“I’m free, walking, talking, and traveling; I have no fears,” Kalugin told The Daily Beast. “I don’t maintain contact with U.S. security unless I need to, and I have no reason to call them at the moment.”

Goslin emphasizes, however, that the Russians “do not play by the same rule book we do.” Former KGB colonel Igor Prelin stated publicly in 2008 that he knows where Kalugin lives and wouldn’t rule out killing him inside the U.S. Subsequently, the U.S. apparently believes there is still good reason to keep tabs on Kalugin in certain circumstances.

“When I travel abroad, there is security provided by the local security people,” Kalugin said. “They are obviously alerted by the U.S. security services, because I don’t ask them for protection. I was in France some time ago for a speaking engagement and as I landed at the airport, a team of security guys introduced themselves and I was surrounded by them the entire time.”

In the United States, high-value defectors are typically debriefed first by the FBI and then handed over to the CIA, which is responsible, by law, for “the secure handling, adequate care, maintenance, rehabilitation, and resettlement of defectors and their families in order to ensure personal safety, encourage other defections, and discourage redefections.”

Enrique García Diaz, a former captain in Cuba’s spy services who defected to the U.S. in 1989, spent two years being debriefed by both the FBI and CIA, resulting in more than 2,000 high-value reports.

When the CIA extracted García from Quito, Ecuador, where he was posted to the Cuban Embassy under diplomatic cover, security concerns forbade him from saying goodbye to his family. A government jet flew García, under heavy guard, to Panama. He was then taken then to a military base in the continental U.S. for a stretch, after which the government installed him in a suburban Virginia safe house.

There, a team of six bodyguards watched over García 24 hours a day; two were even posted in the bedroom while he slept. He was given a new set of American identity documents, as well as a weekly stipend for food and expenses. There was a trial back in Havana, where García was convicted in absentia and sentenced to death.

García still maintains a strict security regimen, the exact details of which he declines to share. Nearly 30 years after defecting, García, who now works as a security consultant and is always armed, is just as vigilant as he was in ’89.

“I always know where all the security cameras are, I always check my car before I get in, when I’m at a restaurant, I always know who is at the tables around me,” García said. “It’s not because I’m worried, it’s because I was trained to do this. It’s automatic, it’s integrated into my life.”

But physical danger isn’t all a defector has to worry about. Many find themselves wrestling with what has been described as “deep psychological shock.” The isolation can be traumatic, and knowing you’ll never see your family or friends again can be overwhelming.

Finding meaningful work is also difficult for many defectors, a good portion of whom are, in Alexandra Costa’s words, “unemployable,” for various reasons. García, who has a law degree from the University of Havana, was lucky; others struggle mightily—past defectors with elite educations and resumes have ended up working as bellhops and dishwashers.

In the end, things turned out reasonably well for Costa, who is now a U.S. citizen. Once a professor in Moscow with a Ph.D. in social sciences and a 154 IQ, Costa’s CIA handlers recommended she enroll in secretarial school. She declined the offer, getting herself into the Wharton School of Business, where she earned an MBA and later ran her own computer consulting business.

Today, Costa lives like any other average American. She enjoys spending time on Facebook, and, is, perhaps unsurprisingly, eagerly looking forward to the final season of The Americans , her favorite TV program.

“As a person who has been there, this show is extremely accurate in their depiction of embassy life,” Costa said. “The only one thing I can fault them on that could never have happened is that FBI agents never meet with sources or targets alone—when I met with the FBI before I defected, they were always two of them. But that’s the only detail on which I can fault them, and of course, they are allowed to have some artistic freedom.”