Interesting parallel. In good old Soviet Union, if you had relatives abroad, you were tainted and were barred from some occupations.
It is necessary to recognize that not only our "enemies" conduct intelligence activities inside the United States. Some of our friends, like Israel and France also have agents here. Much of their activities are what you might call corporate intelligence, trying to pick up information on new technologies in computers, aviation, etc. Research and development is expensive, so sometimes it's cheaper to steal secrets. These allies also want to have political and military intelligence as well. If they have dirt on which Congressmen or which Pentagon officials are having affairs, financial problems, etc., there's a potential to exploit them for information. They may not be our adversaries militarily, but they can use that info in negotiating import/export trade deals, treaties, getting favorable consideration when legislation comes to a vote, or getting a look at the strategies and intentions of our government.