US troops and their allies will shoot Islamic State in Iraq and Syria (ISIS) militants in the face, beat them to death with shovels or drop bombs on them if they dont surrender, the US militarys most senior enlisted member has said. In an eyebrow-raising set of postings on social media on Tuesday, Command Sergeant Major John Troxell warned that ISIS members who refuse to quit will be dispatched with "extreme prejudice," including via a small shovel known as an entrenching tool. "If they surrender, we will safeguard them to their detainee facility cell, provide them chow, a cot and due process," Troxell wrote on Facebook. "HOWEVER, if they choose not to surrender, then we will kill them with extreme prejudice, whether that be through security force assistance, by dropping bombs on them, shooting them in the face, or beating them to death with our entrenching tools," he added. The post featured a photo of a US soldier holding a shovel and, in case anyone was in any doubt about to slay a man with a small spade, Troxell posted a diagram on Facebook on Wednesday explaining exactly how to do so. Troxells chest-thumping remarks quickly attracted a slew of commentary, mostly supportive. Troxells blunt language comes amid a toughening of rhetoric against ISIS under President Donald Trump and Defense Secretary James Mattis. Where then-President Barack Obama said "we will degrade and ultimately destroy" ISIS, Senior US officials, including Defense Secretary Jim Mattis, warned ISIS fighters that they must lay down their weapons or face annihilation. In a related matter, with ISIS being on the brink of defeat in Iraq and Syria, it has resorted ton a "virtual caliphate" -- but even online, experts say it is in decline, according to AFP. Back in 2015, when the jihadists held territory the size of Italy, they also commanded a huge digital presence, flooding the web with slick propaganda lionizing their fighters and romanticising life under their rule. Today, with many of the top ISIS leaders either dead or on the run, what remains of the groups once-sophisticated propaganda machine is also a shadow of its former self. Their media centers destroyed, remaining propagandists find themselves struggling to maintain an internet connection while battling surveillance from international intelligence services. The jihadist group is less and less vocal on the web, largely leaving supporters whom it cannot control to speak in its name. "Its almost as if someone has pressed the mute button on the ISIS," said Charlie Winter, a researcher at Kings College London who has been studying ISIS communications for years. Between November 8 and 9 the group even went completely silent for a full 24 hours in what Winter said was an "unprecedented" break from social media. In 2015, when ISIS was ruling over roughly seven million people in Iraq and Syria, its propagandists produced "content from 38 different media offices from West Africa to Afghanistan", Winter said. But by December, more than three-quarters of these outlets had been "almost totally silenced," he added. Albert Ford, a researcher at US think-tank New America who has studied the exodus of foreign fighters to join ISIS, also said the groups media output was "falling off considerably". "Fewer places to get information, fewer ways to upload it," he said.