One of those affected is Yasir Al-Sayed Issa, who has received threats here in Sweden for his work against the regime in Syria.
"What has affected me the most" he says "is the suspicion that has increased among those closest to me. And in my every day life, I try to make sure I don't leave the house the same time every day, or go home from work at the same time every day. I don't take the same route home every day and I am not out late alone, and stuff like that."
Yasir Al-Sayed Issa has been threatened that his relatives will be in trouble if he does not stop his activism. These threats have also been carried out, as several of his relatives in Syria have been imprisoned, beaten and shot at.
"It is hard to continue after that, because you feel guilty for what has happened to your relatives. It is enough for some people to isolate themselves from the political work, because they cannot cope with it," he says.
According to Wilhelm Unge, head of counter-espionage analysis at the Swedish Intelligence Service, thousands of people in Sweden are scared of reprisals from their home countries.
"It could be the regimes that have people stationed in Sweden, at their Embassy or the chamber of commerce," he says. "There they have the advantage of diplomatic immunity. If we then get wind of their activities, all we can do is perhaps expel the person from the country."
"But they can also be elsewhere in society, like state owned airlines or news agencies - or they could be refugees, such as false refugees that have been placed by the regime for the purpose of infiltrating oppositional organisations and in that way carry out surveillance and thereby threaten their critics."
Unge says these operations have serious implications for democracy in Sweden.
"Many of these people live in such fear that they do not dare to exercise their constitutional rights and privileges and suddenly they do not dare to vote in a certain way in the Swedish elections. This way we begin to get a situation where the Swedish democratic system does not work properly any more."