NEW DELHI: Following two videos showing the execution of American journalists James Foley and Steven Sotloff, the Islamic State (IS) have circulated another video showing the execution of British aid worker David Haines.

At the end, the latest video also showed the militants threatening to kill a second British hostage. Haines has appeared in Sotloff’s execution video, and Sotloff, in turn, had been paraded at the end of Foley’s execution video.

The three execution videos all have marked similarities -- with the victims in orange jumpsuits and the killer speaking with a marked British accent. All three videos show the victims being forced to address the camera, with Foley and Sotloff addressing United States President Barack Obama and linking US airstrikes on IS militants for their execution, whereas Haines addresses British Prime Minister David Cameron.

Whilst the Foley and Sotloff videos began with footage of Obama, the Haines video begins with footage of Cameron speaking about the United Kingdom’s decision to arm Kurdish forces to fight IS. In the voiceover, the killer references US airstrikes in Iraq, specifically strikes that enabled the Iraqi forces to win back the key area around Haditha dam in Anbar province.

Cameron called the murder of Haines an “act of pure evil,” vowing to do everything possible to find the killers. "It is an act of pure evil. My heart goes out to the family of David Haines who have shown extraordinary courage and fortitude throughout this ordeal. We will do everything in our power to hunt down these murderers and ensure they face justice, however long it takes," The Prime Minister said.

The militants, in addition to killing Haines, Sotloff and Foley, have threatened to kill another Briton and have asked for $6.6 million in ransom for an American hostage who was a humanitarian aid worker, whose identity has been kept secret at the request of family members. The militants also asked for the release of Aafia Siddiqui - convicted in 2010 for targeting US officials in Afghanistan.

This latest video comes a few days after US President Barack Obama outlined a four step strategy to fight the IS, focusing on air strikes, support to on-the-ground partner forces, counter terrorism efforts, and humanitarian assistance.

IS militants have been rapidly gaining territory in Iraq, their advances resulting in a political crisis as pressure mounted on Iraqi Prime Minister Nouri-al-Maliki, who is blamed for pursuing sectarian policies, to resign. Whilst Maliki expressed his acceptance of the candidacy of Haider al-Ebadi and the world found their scapegoat, the IS advance shows no sign of letting up.

The militants are labelled Sunni militants, and their rise attributed to divisive policies by the Shia-dominated administration at the centre. Though sectarianism is certainly a factor, this is an oversimplification, especially as sectarianism was not a factor in Iraq prior to the US invasion of 2003. With the US supporting Shia ethno-political parties and propping them to power, a Sunni identity rooted in the context of victimhood, emerged in Iraq. The US support to Sunni militants fighting the Bashar-al-Assad regime in Syria, which includes IS, further facilitated the group’s rise.