Justice Minister Frances Fitzgerald has confirmed that three Irish people have been killed in the conflict zones in the Middle East.
The three young men who died were among up to 30 who travelled to the war zone to fight in recent years.
It is not known if they knew each other, but they all lived in Leinster - in Navan, Drogheda and Dublin.
The youngest victim was Libyan-born Shamseddin Gaidan (16), from Navan, who was killed in February 2013 after travelling to Syria without his parents' permission.
Gaidan moved to Ireland from Libya with his family in 2001. His father, Ibrahim, runs a halal grocery shop in Navan, Co Meath.
The teen spent his summer holidays in Libya in 2012 and was supposed to fly back to Ireland via Istanbul in mid-August.
His family raised the alarm when he did not arrive in Dublin. They later learned he had crossed the Turkish border into Syria.
In Syria, the teenager fought alongside rebel troops against the brutal regime of president Assad but was killed within months.
Gaidan was the second Irish person to die after joining the rebels in Syria.
Egyptian-born Hudhaifa El Sayed (22), from Drogheda, was shot dead in northern Syria in December 2012.
He moved to Louth with his surgeon father but was killed in a gunfight with regime forces before Christmas that year.
Speaking to reporters in Syria before his death, he admitted his parents were concerned.
"They are still worried for my safety out here," he said, but he added that one of his goals in life was "defending the weak against injustice and the oppressors".
In late April 2013, Jordanian-born Alaa Ciymeh (26), who grew up in Dublin, was killed in Syria.
The Ciymeh family, who are Palestinian, moved to Ireland when he was very young.
Ciymeh attended the Muslim National School in Clonskeagh before going on to study at De La Salle College in Churchtown.
He moved back to Jordan in 2008. It is understood that he was not included in the three fatalities announced by Minister Fitzgerald yesterday.
The other man with Irish links to die was Hisham Habbash (29), who was born in Libya but grew up in Ireland.
His family, who live in Dublin, learned of his death in June 2013 through Facebook. Habbash was shot dead near the northeastern town of Raqqa.
The Habbash family, who are Palestinian, moved from Libya to Ireland when Hisham was a child.
Yesterday, Ms Fitzgerald also said that gardai are closely monitoring the activities of a small number of militants here.