Leaked documents from ISIS headquarters show terror group and Syrian dictator Assad colluded over the city of Palmyra
- ISIS and Bashar al-Assad have been colluding, according to leaked files
- Investigation suggests there was co-operation over the city of Palmyra
- Documents also appear to show a deal was made to trade oil for fertiliser
An investigation suggests there was co-operation between the regime and the terror group over the city of Palmyra, which was held by ISIS for nearly a year before it was retaken by Syrian forces in March.
They also appear to show ISIS and the Syrian government made a deal to trade oil for fertiliser.
Leaked documents: One letter, penned before the ancient city of Palmyra was recaptured, read: 'Withdraw all heavy artillery and anti-aircraft machine guns from in and around Palmyra to Raqqa province'
An ISIS defector confirmed ISIS was coordinating the movement of its fighters in coordination with the Syrian army and the Russian airforce
The ancient city of Palmyra was held by ISIS for nearly a year before it was retaken by Syrian forces in March,
The information was revealed in letters - copies of documents sent from ISIS headquarters - which were among 22,000 files obtained by Sky News.
One letter, penned before the ancient city of Palmyra was recaptured, read: 'Withdraw all heavy artillery and anti-aircraft machine guns from in and around Palmyra to Raqqa province.'
Palmyra, a UNESCO World Heritage Site northeast of Damascus known as the 'Pearl of the Desert', was taken back by the Russian-backed Syrian army from ISIS fighters last month.
The city was a major tourist destination before the Syrian conflict erupted in 2011, known for its ancient ruins, colonnaded streets and 2,000-year-old temples.
Jihadis seized Palmyra last year and beheaded its 82-year-old former antiquities chief three months later.
The jihadists destroyed some of the city's most striking monuments and used the ancient amphitheatre as a venue for public executions.
An ISIS defector confirmed to Sky News reporter Stuart Ramsay that the terror group was coordinating the movement of its fighters in coordination with the Syrian army and the Russian airforce.
Another asks for a driver to be able to travel through the terror group's checkpoints 'until he reaches the border with the Syrian regime to exchange oil for fertiliser'.
A letter asks for a driver to be able to travel through the terror group's checkpoints 'until he reaches the border with the Syrian regime to exchange oil for fertiliser'
The Islamic State and Syrian dictator Bashar al-Assad have been colluding, according to leaked documents
The letters also show there were arrangements for ISIS to evacuate areas before Assad's forces attacked.
And they reveal ISIS has been training foreign fighters to attack targets in the West for longer than was originally thought - for years.
Professor Anthony Glees, director of the Centre for Security and Intelligence Studies at the the University of Buckingham, believes such a deal could be a game-changer.
'Deals between two mortal enemies invariably mean one side is winning - but not yet - and the other is losing but isn't defeated and is hoping to stabilise its position,' he said.
'Certainly ISIS has no genuine interest in safeguarding our common cultural heritage. It's about hanging on to weapons and territory. In this case it can only mean Assad and Putin think they are winning and ISIS knows it is losing. But not yet.
'For us in Europe any deal between these two is very bad news. First because both Assad and ISIS terrorise the people in Syria and that will lead to more suffering and more refugees.
'Second it could strengthen rather than weaken ISIS. We in Europe are far less safe if this story is true.
'We in the West are slowly squeezing IS. We should do all we can to prevent them from wriggling loose.'
has been unable to verify the authenticity of the documents obtained by Sky News through the Free Syrian Army.