Sleeper Agents?

Having just read a news item on the FBI giving tours of the tunnel the soviets dug under their embassy, it made me wonder if sleeper agents are still considered a threat by our State Department?



Of all the countries in the world, the USA is most open to sleeper agents. There is such wide acceptance of variety in language and ethnic background that any country wishing to infiltrate agents would not need to go to the trouble that would be necessary for less ethnically varied countries. I cannot believe that the FBI ignores this as a possibility.