More than 850 people have travelled from Britain to Syria and Iraq to join jihadist organisations, while many more have gone out to fight against them.
One of the latest, Chichester chef Ryan Lock, has reportedly been killed in Syria during an offensive by anti-IS forces in a bid to retake the northern city of Raqqa.
The 20-year-old joined Kurdish forces in August.
But he is not the first from our area to travel to the region to join the fighting, which has caused great concern for our local authorities.
Ifthekar Jaman, from Portsmouth, travelled to Syria in May 2013 to fight for Islamic State but was later killed.
His brothers, Tuhin Shahensha, 27, and Mustakim Jaman, 23, were later jailed for six years after bring found guilty of preparing terrorist acts.
The pair helped others and allowed their bank accounts to be used for terrorist purposes.
Perhaps most notably, a group of five men from Portsmouth - naming themselves the Britani Brigade Bangladeshi Bad Boys - travelled to Syria three years ago to join the jihadist cause.
Assad Uzzaman, 25 - cousin of Jaman - Mehdi Hassan, 19, Manunur Roshid, 24, and Muhammad Hamidur Rahman, 25, have all died in the fighting.
Mashudur Choudhury, the last of the group, was jailed for four years for terrorism offences after returning from Syria.
Speaking at a United Nations panel in 2015 following the Paris terror attacks, leading Oxford University academic Scott Atran said three quarters of those who join Isis as foreign fighters were encouraged to do so by friends and peers.
He added that radicalisation rarely occurs in mosques and not through anonymous recruiters and strangers.
The government has also put guidelines in place for schools to help spot signs of students being subjected to radicalisation.
But there have also been concern about Brits who have chosen to travel abroad to join the fight against Islamic State.
A 28-year-old former schoolboy, known as ‘Macer Gifford’, gave up his career in the City to join the Kurdish People’s Protection Units (YPG).
Speaking to the Mail Online in 2015, he said that he ‘passionately’ believed in democracy and free speech.
He added that he wanted to ‘shine a light’ on the plight of the Kurdish people.
The case of Jack Letts, from Oxford, has also received national attention after fleeing the UK to travel to Syria.
The 20-year-old, who has been nicknamed Jihadi Jack, has since said that he disagrees with Islamic State and is not ‘currently’ fighting for them.
But his parents, John Letts and Sally Lane, face a trial this year after being charged with sending their son money which was used to fund terror offences.