LONDON -- Facing all-but guaranteed defeat in their last urban stronghold, Islamic State of Iraq and Syria (ISIS) extremists seem to be relying more heavily on the youngest of their recruits to carryout both attacks, and deliver their propaganda.

For the first time, a child of purported U.S. origin has been put in front of ISIS cameras as a mouthpiece for the terror group.

His message, clearly crafted by adults, seems to acknowledge the terror network's weakening grasp on the vast swath of territory it once held across Syria and northern Iraq, warning President Trump by name that the battle, "is not gonna end in Raqqa or Mosul," but rather "in your lands."

The ISIS propaganda video featuring the alleged American ISIS "cub" was released online Wednesday by the terror group's media operation in Raqqa, Syria. It came out one day after the terror group published photos online of a purported suicide bomber in Iraq, who appeared to be in his early teens, if not younger.

CBS News monitors ISIS propaganda channels online, and while the group's use of child soldiers is not new there has been an increase in the appearance of children in videos and photographs from the battlefields around Raqqa and western Iraq in recent months.

In June, U.S.-backed Kurdish and Arab forces launched an offensive to recapture Raqqa, ISIS' de-facto capital city since the summer of 2014. The battle has grown deadlier by the week, with mounting claims of civilian casualties caused by U.S.-led coalition airstrikes.

Those strikes have enabled the U.S.-backed Syrian Democratic Forces (SDF) to slowly tighten the noose on the remaining ISIS contingent in Raqqa, but militant holdouts -- estimated to be about 2,000 in number -- are entrenched in the center of the city, many with their families.

CBS News cannot confirm the claims made in the ISIS video, including that it was shot in Raqqa and that the boy who appears in it came to Syria with his mother two years ago, when he was eight. He says his father is a member of the U.S. military who fought in Iraq.

Asked about the video on Wednesday, State Department spokeswoman Heather Nauert said the U.S. government could not confirm that the boy is a U.S. citizen and added that, regardless, the video was "depraved. It's another example of how wrong and evil ISIS is."

Read more about this story on CBSNews.com.