Is there any special field in political science to study security issues? In my country, students can follow a special field in political science which is about security issues (like Terrorist, Threats and  opportunities) in Masters programmes. The graduated people can work for Foreign ministry, intelligence services or embassies.

I know the fields in master can vary country by country, but is there any similar fields in German Universities?

What about UK?

If there is, can a non-citizen person study in these fields?
Yes, there are several International Security Studies MA programmes in Germany and in the UK. Examples from Germany include a Master in Peace and Security Studies at the University Hamburg and a Master in International Security Studies at the Universität der Bundeswehr in Munich.

In general, a EU citizen can study in other EU countries. Visa and admission criteria for non-EU citizens vary.