A 4-year-old British boy dubbed “Junior Jihadi” has once again been used in a revolting ISIS propaganda video — this time showing him detonating explosives in a car with three captives strapped inside.

Isa Dare — who was taken to Syria by his mom, Grace “Khadija” Dare — is seen with a young man who addressed the UK with a scarf covering his face.

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“You will never fight us except behind fortified fortresses or behind walls,” he said, the Independent of the UK reported.

He then mentions spies sent to Syria and the killing of “our brothers” in the West.

“So today, we’re going to kill your spies the same way they helped you kill our brothers,” he said. “So prepare your army and gather your nations, for we too are preparing our army.”

The three doomed captives, wearing the familiar orange jumpsuits, first offer their “confessions” before being cuffed inside the vehicle.

Little Isa, clad in combat fatigues, makes an “OK” sign, presses a detonator to blow up the car and yells “Allahu akbar!” — “God is great.”

British Prime Minister David Cameron’s spokeswoman said officials were studying the vile video — insisting it was proof that ISIS is losing ground in Syria and Iraq.

“As we’ve said before, releasing such propaganda is an example of a terrorist group feeling under pressure,” she said.

The exploitative video is believed to have been shot in Raqqa, ISIS’ de facto capital in Syria.

Last month, Isa was seen gesturing toward what appeared to be the same car in another execution video.

Henry Dare, Isa’s grandfather, has accused ISIS of using the youngster as a “pawn” in its twisted propaganda.

The boy’s mom was raised as a Christian but converted to Islam before leaving her home in Lewisham in 2012 with baby Isa. She married Swedish jihadist Abu Bakr, who is believed to have since been killed.