"What do you want to be? A jihadist, or to execute a martyrdom operation?"

In the "caliphate" recently proclaimed by jihadists in Syria and Iraq, even young children are indoctrinated, and Sharia law is backed by the gun, according to a gripping documentary offering one of the first glimpses of life in Raqqa, power base of the so-called Islamic State (IS).

Part 1 of a five-episode series, The Islamic State, filmed by Anglo-Palestinian journalist Medyan Dairieh was released Thursday by New York-based Vice News.

The tone is set early: "Sharia can only be established with weapons," an IS fighter explains to Dairieh, who spent three weeks embedded with the radical Sunni group.

Dairieh, toting a video camera, gained "unprecedented access" to the organization, Vice News said.

In Raqqa, heavily-armed jihadists are seen celebrating on US armored vehicles seized during their advances in Iraq, while Sharia police patrol streets and markets with rifles over their shoulders.

Patrol chief Abu Obida orders traders to remove a poster showing "infidels," then blithely tells a man to change the fabric on his wife's veil.

"Those who don't obey will be forced," Obida explains.

In one gruesome scene, a crucified murder convict is displayed in the public square. In another, the bodies of Syrian 17th Division soldiers, killed by the jihadists during a recent offensive, are dumped on the sidewalk, their severed heads impaled on gate spikes.

"The Islamic caliphate has been established, and we will not stop," said IS press officer Abu Mosa.

A bearded man with a penchant for Ray-Ban sunglasses, Mosa accompanied Dairieh on his reporting and was shown shooting at Syrian soldiers during a skirmish.

He portrayed the group's fight as a battle against infidels like those in the West.

"Don't be cowards and attack us with drones. Instead send your soldiers, the ones we humiliated in Iraq," Mosa said of the Americans.

"We will humiliate them everywhere, God willing, and we will raise the flag of Allah in the White House."

- Child training camps -

Young boys look into the camera and pledge to take up the cause to "kill infidels."

A nine-year-old preparing for Kalashnikov rifle training said he was learning "to fight Russians -- umm, America."

"What do you want to be? A jihadist, or to execute a martyrdom operation?" a man identified as Abdullah the Belgian asked his six-year-old son.

"Jihadist," the boy replies, saying under prompting that infidels "kill Muslims."

Boys under 15 attend Sharia camp, while older ones learn military operations.

"We believe that this generation of children is the generation of the caliphate," said one man while children splashed in the Euphrates river.

"The right doctrine has been implanted in those children," he added. "All of them love to fight for the sake of building the Islamic State and for the sake of God."

Few women can be seen in the documentary; those who are shown wear the hijab.

Dairieh leads viewers through a courthouse where residents file complaints or wait on rulings from a Sharia judge on matters related to finance, alcohol use, adultery and other personal matters.

Asked if the process meets international standards, a clerk declares: "We aim to satisfy God, that's why we don't care about international standards."

Following a lightning offensive across Iraq in which IS was accused of numerous atrocities, the group on June 1 declared its caliphate from northern Syria to parts of eastern Iraq. Hundreds of thousands of people have fled.

Within days, jihadists advanced on autonomous Kurdistan, driving tens of thousands of minority Christians and non-Muslim Yazidis from their villages.

IS media coverage has been exceptionally rare due to security reasons. A New York Times report on the group last month did not identify its author or persons interviewed.

The brutal violence -- which has reportedly claimed the life of Mosa and another IS official since they were featured in the documentary -- makes Dairieh's time behind the IS veil extraordinary.

Kevin Sutcliffe, Vice News head of news programming for Europe, said Dairieh is likely "the only person they've let in for this amount of time."

The news outlet, part of Vice multimedia group, launched last December. Vice notably claimed a role in the 2013 "basketball diplomacy" which saw ex-NBA star Dennis Rodman travel to North Korea to meet leader Kim Jong-Un.