Adeel Ulhaq, 21, of Westbourne Drive, Sutton, is charged - along with two other men - of helping Cardiff teenager Aseel Muthana who fled to join the terror group in February.
Jurors heard he followed in the footsteps of his older brother, Nasser Muthana (21) who travelled to Syria with four pals a few months earlier.
Nasser Muthana became one of the dubious ‘stars’ of the notorious terrorist propaganda video “There is no life without jihad”, which was released last June to encourage westerners to join ISIS.
Prosecutors say Ulhaq (pictured), along with Forhad Rahman (21) and Kristen Brekke (19) helped Aseel, now 18, to travel to Syria to join IS and are guilty of terror offences.
Rahman, who allegedly helped Muthana to get a passport, bought his plane ticket and even paid for his coach to Gatwick Airport, formed an ‘intense friendship’ with his pal online, the court heard.
Rahman, from Cirencester, also put Muthana in touch with Ulhaq, so that he could advise him about how to make it to Syria in online chats before and after he left the UK, it was said.
“The advice he gave in those discussions showed that, despite his youth, Adeel Ulhaq had both a great deal of knowledge about the armed conflict in Syria and a network of contacts who could be of use to people seeking to get involved in it,” said prosecutor Christopher Hehir.
‘In going to Syria to join the ranks of Islamic State, Aseel Muthana was acting so as to become involved in terrorism: he was going to join a group who use violence in pursuit of political, religious and ideological – but above all religious – aims.
“Islamic State is one of a number of radical Islamist groups fighting to overthrow the regime of President Assad.
“The prosecution say that each defendant, when he helped Aseel Muthana travel to Syria, did so in the full knowledge that Aseel Muthana was going there to fight with Islamic State, and they wanted to help him do just that.
“In those circumstances each is guilty of the offence of preparation of terrorist acts with which he is charged.”
Ulhaq was allegedly introduced to Muthana by Rahman and his contact with Aseel was entirely by telephone and online, Mr Hehir explained.
“The prosecution case is that all three defendants shared, with each other and Aseel Muthana, the same radical Islamic ideology and support for those waging armed conflict in pursuance of that ideology in Syria,” continued the prosecutor.
“Indeed two of the defendants, Forhad Rahman and Adeel Ulhaq, were part of a network of friends and acquaintances in various places with a similar outlook.’
Mr Hehir said that although the defendants as well as the Muthana brothers were all Muslims, ‘nobody is on trial for his religion’.
“In our democratic society all are free to hold any religious belief, or none.
“What people are not entitled to do is engage in, or assist others to engage in, the use or threat of violence in pursuit of a religious cause, here or abroad.
“Nor is this trial about the rights and wrongs of the conflict in Syria,” he told jurors.
“Your task is not to decide who the good guys or the bad guys are in that conflict.
“You may think that in a bitter civil war such as that which has raged in Syria, finding anyone who could truly be called the good guy s would be a difficult if not impossible task.”
Rahman, of Cranhams Lane, Chesterton, Cirencester, Gloucestershire, Brekke, of Pentre Street, Grangetown, Cardiff, and Ulhaq deny preparation of terrorist acts.
Ulhaq also denies funding terrorism by making a money transfer to someone fighting in Syria.
The trial continues.