Secretary of State Rex Tillerson's team condemned the apparent use of an American child in a propaganda video released by the Islamic State.

"Any child used in that capacity in an ISIS video regardless of what is being done, it's sick," State Department spokeswoman Heather Nauert told reporters. "It's sick and it's depraved."

ISIS reportedly released footage of an American child described as the son of a former U.S. military service member promising that the terrorist group would strike the United States. Notably, the propaganda video seemed to acknowledge the group's impending loss of its last major strongholds in Iraq and Syria, albeit in a defiant tone.

"This battle is not gonna end in Raqqa or Mosul," the child said in the video, according to the Daily Beast. "It's gonna end in you[r] lands."

Nauert avoided commenting on the speaker. "I can't confirm if that child is an American," she said.

The threat contained in the video, however, points to a problem that U.S. officials have warned will have to be confronted — the danger that ISIS will revert into a dangerously decentralized terrorist group after their so-called caliphate is destroyed. "We all know, there will be a terrorist diaspora out of the caliphate as military force crushes the caliphate," then-FBI Director James Comey told lawmakers in July of 2016.

But she linked the footage to a broader pattern of ISIS exploiting children for terrorist purposes over the last several years. "[ISIS has] used them as human shields; we've seen ISIS use children the ages of some of our own children as suicide bombers, as homicide bombers," Nauert said. "It's sick, its depraved and it is another example of just how wrong and how evil ISIS is."

Such terrorist tactics at times have slowed the counter-ISIS coalition in executive offensive operations. U.S. leaders, however, are also trying to mitigate the "diaspora" danger by encircling ISIS positions and then methodically killing every foreign fighter who in the terrorists' midst.

"And the foreign fighters are not coming into Syria anymore, and those who are already in Iraq and Syria we've been working very hard to make sure that they can never get out," Brett McGurk, the State Department official coordinating the counter-ISIS campaign, told reporters in July.