syria coalition air strikes 2016
The US-led coalition has confirmed the death of Isis second-in-command Haji ImamREUTERS/Kadir Celikcan

The Pentagon has confirmed the death of senior Isis commander Haji Imam in a daring daylight US-led raid in Syria. Imam was considered by many to be a potential successor to leader Abu Bakr al-Baghdadi. Imam's death comes just weeks after the killing of Tarkhan Tayumurazovich Batirashvil, also known as Omar al-Shishani or Omar the Chechen, and represent yet another setback for the Islamists in the areas of Syria and Iraq in which they aim to create a caliphate.

The death of Imam – also known as Abd ar-Rahman Mustafa al-Qaduli – was announced by US defence secretary Ash Carter and Joint Chiefs Chairman Gen Joe Dunford at a Pentagon press conference. It is reported al-Qaduli was killed as special forces were attempting to arrest him. Three others linked with al-Qaduli died during the operation.

Chechen Isis leader Omar al-Shishani
Omar the Chechen was killed in a US air strike

Some observers have questioned the assertion that al-Qaduli could become Isis leader due to his Turkmen background. However such was his importance to the group that in 2015 Secretary of State John Kerry authorised a $7m (£4.9m, €6.2m) reward for information leading to his capture. Prior to joining Isis he had been linked with al-Qaeda and is once thought to have been the right hand man of notorious killer Abu Musab al-Zarqawi, whose group of thugs beheaded Briton Kenneth Bigley and other Westerners in 2004. al-Zarqawi was killed in an air strike in 2006.

As the death of Tarkhan Tayumurazovich Batirashvil following an air strike demonstrated, Isis has suffered a series of military setbacks in recent months and the area of land they control in the region is shrinking. There have been persistent rumours that al-Baghdadi himself is seriously ill or injured and has fled the Isis "capital" in Iraq, Mosul. However as Brussels, Paris and San Bernardino demonstrated Daesh retain the power to organise and inspire terror outrages beyond the Middle East even as their influence within the region begins to wane.