The European Union said Monday it remains "fully committed" to tackling the threat posed by the Islamic State extremist group after it beheaded US aid worker Peter Kassig.
EU foreign policy chief Federica Mogherini and humanitarian aid commissioner Christos Stylianides said in a statement that the killing of Kassig and 18 men described as Syrian military personnel showed IS's "resolve to pursue its terror agenda in breach of all universally recognised values and rights."
"All perpetrators of human rights abuses must be held accountable. The EU will spare no effort towards this objective," they said in their statement.
"We remain fully committed to tackling the threat posed by ISIL and other terrorist organisations in Syria and Iraq, alongside our regional and international partners."
EU countries Belgium, Britain, Denmark, France and the Netherlands are participating in US-led air strikes against Islamic State in Iraq, but no EU country is taking part in the strikes against the group in Syria.
A video released by IS militants showed the beheading of Kassig, who took the name Abdul-Rahman after converting to Islam, and that of 18 men described as Syrian military personnel.
Kassig's death was confirmed by President Barack Obama.
The 26-year-old was captured last year and was threatened in an October 3 video showing the beheading of British aid worker Alan Henning.