A leading member of the Turkish Humanitarian Relief Foundation (IHH) who participated in the 2010 Gaza flotilla incident has been killed in U.S.-led airstrikes targeting Islamic State group positions in Syria.

Reports emerging from Turkey and Israel suggested that Yakup Bulent Alniak, 40, had traveled to next-door Syria to fight alongside the terrorist group the Al Nusra Front, while other reports said he was aligned with the Islamic State group. Yet other reports suggested he was in Syria to research a book and distribute food aid.

The IHH – along with U.S. and European pro-Palestinian activists – launched the flotilla to try to break the Israeli blockade of Gaza, which Israel maintains is aimed at preventing the shipment of weapons to Hamas.

When Israeli naval troops boarded the Mavi Marmara – the boat on which the Turkish activists were sailing - to enforce the sea blockade, they were attacked with knives and metal bars. Nine Turkish citizens were killed, among them eight IHH activists.

Top IHH member who was on Gaza flotilla is killed in US strike while fighting for ISIS http://t.co/9XG3tGIu1t pic.twitter.com/isULvDN5lw

— Oren Kessler (@OrenKessler) September 28, 2014

Anti-Israel activists at the time described the Gaza boat mission as “humanitarian” in nature; however, a subsequent investigation by an Israeli research organization revealed that one of the IHH activists, 19-year-old Furqan Dogan, hinted he expected trouble when he posted this entry in his diary while on the mission, “These are the last hours before I join the sweet experience of being a shahid (martyr). Is there anything more beautiful than this?”

IHH is designated by Israel as a terrorist group.

According to Israel’s Ynet, Alniak who was killed in Idlib, Syria, was “one of those who were directly engaged in attacking the Israeli troops” who boarded the boat.

Ynet quoted Turkish reports over the weekend which said that Alniak had recently joined the Islamic State group and was “directly involved" in combat.

Ynet quoted from one of his last Facebook posts, which read, “My life and death are for Allah.”

Israel’s Arutz Sheva quoted the Turkish website T24 which stated that Alniak was fighting with the Al Nusra Front.

Israeli Foreign Ministry spokesman Emanuel Nahshon told Ynet that Alniak’s case suggests "a direct line that connects the extremists of the IHH organization to the murderers in ISIS. He who tried to harm IDF soldiers found himself a career as an executioner in the service of extremist Islam."

Other reports suggested his presence in Syria was not military in nature.

World Bulletin, a Turkish publication, reported that Alniak had traveled to the battlefield to distribute food to “Syria’s needy,” while the Investigative Project on Terrorism quoted a statement from a Turkish charity group, Iyilikder, which said the activist was in Syria to research a book.

Turkish anti-terror police in January raided the offices of IHH and detained 28 over suspicions of smuggling weapons to Al Qaeda-linked jihadi rebels in Syria.