An Australian police officer posed as a wannabe terrorist to bring down an American troll who wanted to incite a terror attack in Melbourne from his Florida basement.

Joshua Ryne Goldberg, 23, was jailed for 10 years by a US judge last month after a court heard evidence of his role in bizarre online terrorist plots.

A sentencing hearing was told an undercover Federal Police (AFP) officer struck up a conversation with Goldberg on Twitter in mid-2015.

The operative convinced Goldberg he was a Melbourne jihadist who was hoping to kill 'filthy kuffar', the Arabic term for 'unbelievers', court documents said.

Florida man Joshua Ryne Goldberg, 23, was jailed for ten years by a US judge last month after a court heard bombshell evidence of his role in bizarre online terrorist plots

One of many fake Twitter accounts associated with Florida man Joshua Ryne Goldberg

One of the gunmen who opened fire on the 'Muhammad Art Exhibit and Cartoon Contest' in Garland, Texas, in 2015 copied one of Goldberg's inflammatory tweets, a court heard. Both gunmen were killed and a security guard was wounded

Internet-addicted Goldberg first caught the attention of police both here and in the United States after he began posing as an Australian extremist on social media.

Goldberg posted messages calling for extremists to attack an art exhibition in Texas which featured artwork depicting the Prophet Mohammed.

Two gunman heeded the call but were shot dead by a security guard before they could kill anyone at the Curtis Culwell Center in the town of Garland on May 4, 2015.

Elton Simpson, one of the shooters, retweeted one of Goldberg's posts that day. Goldberg later claimed online that he had 'inspired' the shooting.

Within weeks, Goldberg thought he had found someone else on Twitter who was willing to commit terror in a young man from Melbourne who was purporting to be an extremist.

But he had no idea he was actually talking to an Australian Federal Police officer, who did not actually mean it when he told him: 'i cant wait to cut down these filthy kuffar'.

Court documents revealed the officer described himself to Goldberg as a second-generation migrant seeking to reclaim his Islamic heritage.

'My parents moved to australia before I was born and adopted the western way. i hate them for this,' the undercover operative told Goldberg.

'I have grown up with western kafir (non-believer) brainwash and i can see this now as i get older.

'I guess for me i want to reclaim my islamic heritage which was stolen from me'.

Twitter messages between an undercover Australian Federal Police officer (blue) and Joshua Goldberg (grey) as contained in US court exhibits

This is the Orange Park, Florida home where a court heard internet troll Joshua Ryne Goldberg spent his time trying to arrange terrorist attacks in Australia and the United States

When the agent asked Goldberg he had ever thought of leaving Australia for the 'Islamic State' in Syria and Iraq, Goldberg suggested they attack local targets.

'I believe it would be better if both of us carry out jihad on Australian shores,' he said, according to the sentencing exhibits.

'We need to carry out jihad against Jews. There are many synagogues in Melbourne to target'.

The agent replied: 'What have you got in mind?? I don't have a gun but my brother's friend are pretty shadey characters - maybe they have one haha'.

As the weeks went by, the agent claimed he had obtained a rifle - but wanted two things: an Islamic State flag and for his friend to be martyred alongside him.

A picture of a rifle the AFP officer sent Goldberg as evidence of the 'gun' he had apparently obtained

A Surespot message sent from the undercover operative to Joshua Ryne Goldberg

An impatient Goldberg hounded the agent - who even claimed to have got himself a gun - to launch attacks 'this weekend', the sentencing documents show.

'I am just not ready and completely prepared to commit jihad until my melbourne brother is ready,' the agent told Golberg.

The fake Melbourne jihadist lost patience with Goldberg - telling him 'you need to relax' after he demanded he launch a terrorist attack 'this weekend'

'I would not be a good Muslim if I didn't give him a chance to become a shaheed (martyr) with me.

'He wants to use a knife to be able to cut up the kuffar, inshallah that can happen soon.

'This is so important to me. And it needs to be done correctly for me to become a Shaheed and rise to jannah (heaven). '

Goldberg said: 'You gotta commit to this Saturday, akhi. This is our last chance.

'Allah has given us this perfect opportunity.

'No more excuses, akhi. This is Allah's will. Allah's will does not seek excuses.'

He shared timetables showing when Jews would be praying at a synagogue in Melbourne's south-east.

Goldberg, centre, insisted the undercover Australian operative launch an attack on a Melbourne synagogue

But the undercover agent said: 'Salaam akhi (brother), you need to relax and stop putting so much pressure on me....

'This is my life akhi, i will make up the time to commit my jihad and the pressure ur putting on me is not healthy.

'i know i have the gun, I know I can commit the attack but it needs to be the right time for me akhi.'

The agent pledged: 'I will die as a Shaheed (martyr)!'

But it was all a ploy, and it wasn't the only one Goldberg had been suckered into.

About the same time, Goldberg was involved in a separate terror plot, the court documents said.

He was encouraging a FBI confidential human source to drive to Kansas City and let off a bomb at an event commemorating the September 11, 2001, terrorist attacks.

He sent the FBI source a series of instructions on how to build a pressure-cooker bomb, court documents said. It led to his arrest the day before the memorial, on September 10, 2015.

He was charged with illegally distributing information relating to explosives, destructive devices, and weapons of mass destruction and pleaded guilty to the offences late last year.

He admitted to his role planning the attacks in Australia in an interview with FBI agents.

'I figured it would be a place a jihadist would attack, so I suggested go attack a synagogue,' he said.

Goldberg claimed to investigators he had been planning to turn in the terrorists before they launched their attacks and believed the Kansas City pressure cooker bomb would blow up in its owner's face.

In his FBI interview - contained within court transcripts - Goldberg was asked: 'Why did you really do it?'

He replied: 'I told you, because I thought I could be a real journalist ...

'I would have tipped off the police and then written a story about it about the case with, with like, investigation that was really from me being AustraliWitness,' he added later.

Goldberg was stunned at his predicament the morning of his arrest.

'It just doesn't feel real,' he told FBI officials.

'I guess I never really see things as real, this whole world always felt like, like it's a dream or something'.

The Australian Federal Police declined to comment.