By itself, living in the United States is no guarantee of safety. Suspicious deaths of Russian expatriates have occurred on U.S. soil in the past. In November 2015, for example, former Russian media tycoon Mikhail Lesin, the founder of the RT media outlet, was found dead in his hotel room at Dupont Circle, in Washington, D.C. His death, at first reported to be from a heart attack, was later attributed to blunt force trauma. Although he resided in California in the years before his death, Lesin was not under U.S. protection, and despite strong suspicions of Kremlin involvement in his death, no connection was proved.
In the Skripal case, after the British government's accusations against Russia surfaced, the United States moved to expel known Russian intelligence officers
from the country. That will ease the task of FBI surveillance teams that keep tabs on the remaining Russian operatives who are suspected of engaging in espionage — or who could orchestrate an attempt on a Kremlin enemy's life. Granted, in its quest to harm enemies of the state living in America, Russia could hire contract assassins or enlist the help of organized crime, but U.S. federal law enforcement agencies also have units dedicated to keeping tabs on these kinds of criminals.
If, in fact, the Skripals are relocated to the United States, there are three agencies that might handle the job of protecting them. Which one the National Security Council assigns the task to would likely never be made public, but they are fully capable of ensuring that Russian intelligence services never touch the Skripals again.
The first option could be the U.S. Marshal's Service, which runs the U.S. Federal Witness Protection Program, or WITSEC
. Informants and protected witnesses entering the program receive a complete identity change, including new official government-issued documents. A WITSEC inspector (who is a deputy U.S. marshal) is charged with keeping the protectee and his or her family alive, an operation colloquially known as "care and feeding," and has a range of duties from operational security to helping the protectee find a job. I saw the WITSEC program in action in person when I was a State Department special agent, and I can tell you that these folks are good. Protectees are expected to play by the program's rules, including cutting all ties with their past, even family. Those who do not quickly find themselves fending for themselves. Success of the program depends upon following security protocols and secrecy, skills that a former spy or defector would possess. Let's face it, the Skripals know better than most the nature of the threat, as they barely survived the poisoning attempt.
The CIA would provide the Skripals another option, with a group of protective security officers with guns and badges who are accustomed to keeping a close eye on defectors. These highly trained and specialized protection officers specialize in surveillance detection and the effective use of safe houses (I've also worked with them in the past.) Due to the nature of the protection business, short-term stays for protected sources can take place at highly secure CIA training facilities and military bases. Cities that have less of a Russian presence would be favored destinations, in order to lessen the odds that a chance encounter would blow the Skripals' cover. The local FBI office would also be looped in so its agents could be on the lookout for intelligence that Russian assassins are on the hunt.
The FBI itself could provide a third option for ensuring the Skripals' safety. If the bureau got the assignment, a dedicated case agent from one of its Russian squads would work directly with the Skripals, augmented by FBI special surveillance group officers. Discreet notifications to local police intelligence units would result in enhanced patrols around the specific residence that the Skripals eventually inhabit. For the most part, the cops are never told why the location is important, but enhanced coverage means that any suspicious events or incidents — or 911 calls — would receive priority treatment, including alerting a SWAT team.
As you can see, the United States can offer several options for ensuring that the Russian intelligence service would have little chance to take another shot at the Skripals. While it's never realistic to expect airtight security, the odds certainly would tilt in the favor of the Skripals if they were relocated to the United States.