The jihadist militia Islamic State (IS) has threatened retaliation after the death of its former leader Abu Ibrahim al-Hashimi al-Kuraishi.
"Trusting in God, we announce a blessed campaign to take revenge," the militia announced in an audio message on Sunday.
The new IS spokesman Abu Omar al-Muhajir also called on IS supporters to carry out attacks in Europe again.
ISIS supporters should seize the "opportunity" when "the Crusaders fight each other," al-Muhajir said, referring to Russia's war against Ukraine.
According to the US government, al-Kuraishi blew himself up during a US operation in northwestern Syria in February.
In March, IS militia confirmed his death and that of their former spokesman, Abu Hamsa al-Qurayshi.
Abu Hassan al-Hashimi al-Kuraishi was appointed the new leader.
militarily defeated in 2016
In 2014, IS conquered large regions of Iraq and Syria.
Even after the military victory of a US-led international coalition over the so-called caliphate set up by IS in 2016, the militia remained active in the region.
A UN report last year concluded that there were still around 10,000 active IS fighters in Iraq and Syria.