I don't know how much of this you know, but there are several "dissident" republican and loyalist terror groups that have remained active since the Good Friday Agreements. The Omagh bombing, with the biggest loss of life of any attack in the Troubles, was carried out by dissident republicans after the agreement. The last republican bombings on British soil (not in Northern Ireland) were by the Real IRA in 2001, but they've continued in Northern Ireland, including in the past few years.
I know about the IRA in general from the news & living in the UK. I hadn't realised splinter groups were still at it.
I don't tend to read the news -- so haven't heard much about Sinn Fein[0] recently, for example. Looking up SF, I've just learned they are left-wing. I'd assumed they were right-wing nationalists.
Guess the answer to how much I know about this subject is, a wee bit.
[0] https://en.wikipedia.org/wiki/Continuity_Irish_Republican_Ar...