What issue has cause tension in northern ireland

the issue that caused tension in Northern Ireland is the conflict between Unionists/loyalists and Nationalists/republicans

Explanation:

In the Northern of Ireland is develop a conflict between to political parties in one side are the Union/loyalists these are mainly protestants and want Ireland to remain in the United Kingdom.  

On the other side are the Nationalist/republicans who are mostly catholic and want Ireland to leave the United Kingdom and create a United Ireland.  

citizens get the vast majority of their political and governmental information from the media, which includes television, print journalism, radio, and now the internet. the media play an important role in connecting people to government.

lots of people lost money in both