“The talk of a truce I don’t make much of,” says Gartenstein-Ross. “I take it much more as a tactic designed to break the morale of their opponents and to give credence to antiwar voices in the West.”

He adds: “ISIS is very attuned to the different audiences it wants to influence and fairly effective in how it does that, and here, I think, it is seeking to appeal to those in the West who have unease about the military action that is being undertaken taken with the aim of eroding the enemies’ political will.”

Cantlie has certainly been used in the past by the militants to offer, in video and written commentary, a counter-narrative to Western audiences, one that seeks to sap the morale of the West, pour scorn on Western media reports and legitimize the caliphate announced in the summer by ISIS leader Abu Bakr al-Baghdadi.

In March, a former hostage, Spanish journalist Javier Espinosa, disclosed that during his time in captivity, Cantlie twice tried to escape and suffered “weeks and weeks” of torture as a result. Cantlie’s punishment for trying to flee the extremists was so harsh that the journalist almost drowned during one waterboarding session.