Iran to send 4,000 troops to support President Assad in Syria as British Armed Forces play war games on border 350 Royal Marines on way to Jordan as part of 'multinational exercise' David Cameron welcomed Barack Obama's vow to provide 'military aid' to Syrian rebels but has so far only promised Britain's 'non-lethal' support Britain and U.S. to tackle Putin for supporting Syria's president at G8 meet Videos on YouTube shows rebels with shoulder-fired heat-seeking missiles Clips prompt fears arming rebels will put weapons in hands of extremists Iran is preparing to send 4,000 troops in to Syria to support Syrian President Bashar al-Assad in the wake of America's announcement it will be providing 'military aid' to the country's Muslim rebels. President Barack Obama made the pledge earlier this week after the U.S. claimed it found 'conclusive evidence' Assad's regime has used chemical weapons against the rebel forces - which includes the most extreme Sunni Islamists - and has called for Britain and France to back the move. While Britain hasn't made a guarantee either way as yet, more than 350 Royal Marines are being sent to Jordan as part of an 8,000-strong 'multinational exercise', further increasing tensions in the war-torn region. Concerns: Footage posted on Youtube shows a Syrian rebel with a shoulder-fired heat-seeking missile which can target planes up to 11,000ft in the air - and raising questions over how well-armed forced already are in the country Risk: The footage has further prompted fears that arming Syria's rebels could cause powerful weapons to fall in to the hands of anti-West extremists Sources claim the 12-day exercise, called Eager Lion, is part of a plan to have Nato troops on hand for humanitarian ­purposes in Syria. But as the West debates whether to proceed with 'military intervention' in Syria, where 100,000 people have been killed in the last two years, a video has emerged online showing an Islamist fighter using a surface-to-air missile. The footage shows the fighter targeting a helicopter with a shoulder-fired heat-seeking Soviet-era SA-16 missile which can hit planes flying at 11,000ft. It has sparked fears that the arming of moderate rebels will lead to weapons falling in to the hands of extremists who would want to target the West. It comes as the entire Middle East region threatens to plunge into the growing conflict, which has become a hardline divide between the Sunni Muslims and Shiites, after it emerged Iran is preparing to move troops in to Syria to support Assad. Taking action: President Barack Obama, pictured right, has vowed to give 'military aid' to the Syrian rebels - a move which has been welcomed by Prime Minister David Cameron, pictured left earlier this month More than 100,000 people have lost their lives in the conflict, pictured in Western Dumayna, in two years The military decision to support Assad was made even before Iran's Presidential election earlier this week, according to The Independent. The entire region is becoming increasingly torn between Sunnis who believe that the father of Mohamed's wife was the new caliph of the Muslim world and Shias who regard his son-in-law Ali as his rightful successor. America now finds itself on the side of the wealthiest states and Sunni territories of the Arab Gulf - from Egypt to Morocco, Turkey and the British-created monarchy in Jordan. On the other side of the divide is Iran and the largely Shiite Iraq which the West 'liberated' from Saddam Hussein's Sunni minority in the hope of balancing the power of the region. But as well as causing a divide between the Sunni and Shiite factions of the Middle East, tensions are increasing between America and Russia. Russian President Vladimir Putin has made no secret of his opposition to any move by the West to supply arms to the Syrian opposition. Holding firm: President Bashar Assad has accused the West of backing rebels linked to al-Qaida-linked during his country's civil war Growing tensions: David Cameron and President Barack Obama will be taking Russia's President Vladimir Putin, pictured together in last year, to task over his support of Syrian President Assad's regime He responded to the recent lifting of the EU arms embargo by reaffirming his intention to supply President Bashar al-Assad with sophisticated anti-aircraft missiles in order to deter 'hotheads' from intervening in the conflict. And following America's announcement it will provide 'military aid' to Syrian rebels, Assad this weekend suggested on Lebanese TV that Syria may have received the first shipment of an advanced Russian air defence system after Moscow promised S-300 missiles. David Cameron is due to meet with Mr Putin for talks on the Syrian crisis amid fears that differences between Moscow and the West are pushing the two sides towards a new Cold War. David Cameron has been forced by his own backbenchers to promise a Parliamentary vote on Britain providing military support to Syrian rebels The Russian president has reacted sceptically to evidence produced by Britain, France and the US that the regime has used chemical weapons - crossing Mr Obama's 'red line' for intervention. Mr Cameron has welcomed Mr Obama's announcement, although he has yet to decide whether to follow the president's lead on supplying arms to the rebels. However he said Britain would continue to offer non-lethal support to what he called the 'genuine' opposition - saying it was vital to bolster the democratic elements against the extremists. Yes there are elements of the Syrian opposition that are deeply unsavoury, that are very dangerous, very extremist and I want nothing to do with them. I'd like them driven out of Syria - they're linked to al Qaida,' he said in an interview with Sky News's Murnaghan programme. But there are elements of the Syrian opposition who want to see a free democratic, pluralistic Syria that respects the rights of minorities including Christians and we should be working with them - we are working with them. 'If we don't work with those elements of the Syrian opposition, then we can't be surprised if the only elements of the Syrian opposition that are getting, that are actually making any progress in Syria, are the ones that we don't approve of. 'After all, they are trying to defend their communities against appalling attacks, including, let's be clear, chemical weapon attacks. President Assad is now guilty of the most appalling crimes against his people - 90,000 people dead and some of them through the use of appalling chemical weapons. Clash of opinions: Syria will be a major topic at the meeting of the G8 leaders - depicted by members of Oxfam today ahead of the start of the summit Egyptian President Mohammed Morsi yesterday announced that he was cutting off diplomatic relations with Syria and closing Damascus' embassy in Cairo amid growing calls from hard-line Sunni clerics to launch a 'holy war' against Syria's embattled regime Even if Mr Cameron were to decide that Britain should start supplying arms, he may find his path blocked in the face of strong opposition in Parliament across all three main parties. The Prime Minister again reaffirmed the commitment wrung out of him by Tory rebels that he would give MPs a vote if he decided Britain should go ahead and arm the Syrian opposition. I think Parliament should have a say about these things. I can't really go further than that,' he said. Meanwhile Nick Clegg struck a decidedly cautious tone over Syria today, raising questions about how much support there is in government for David Cameron's increasingly hawkish stance over the conflict. Battle: Syrian rebel fighters belonging to the 'Martyrs of Maaret al-Numan' battalion leave their position after a series of shootings in the northwestern town of Maaret al-Numan earlier this week Civil war: A vehicle is seen burning in the village of Buweida, north of Qusayr, in Syria's central Homs province as regime forces sought to mop up the final pockets of rebel resistance north of Qusayr earlier this month Ahead of a meeting between the prime minister and Russian president Vladimir Putin, Clegg told the Andrew Marr programme that arming the rebels was 'not the right thing to do now at this point'. He added: 'We're trying to strike the right balance between playing a part with other allies but not embroiling this country in military conflict in a way I don't think would be acceptable to the British people.' Asked whether the deputy prime minister's more cautious tone suggested the Lib Dems were prepared to oppose intervention in the same way they opposed war in Iraq, Clegg was keen to point out the differences. 'This is not like Iraq and it's different to Libya as well. This is a bloody civil war. The idea we can provide a unilateral British military solution to this is fanciful,' he said. Cautious: Deputy Prime Minister Nick Clegg today told presenter Jeremy Vine on Andrew Marr Show that arming rebels is not the right thing to do at 'this time' Former Lib Dem leader Lord Ashdown said it would be 'an act of very considerable folly' to start arming the rebels. He warned that the West risked being drawn into a wider sectarian struggle between Sunni and Shia Muslims who are backed by Iran and Russia. This not about Syria. We think Syria is the issue, it's not. It's the front line in a much, much wider struggle,' he told the Murnaghan programme. The issue now is not tackling the Great Satan of the West, it is preparing for a war against the Great Heretic in Tehran. 'I don't believe that it is sensible for us to be contributing to that process.' Now watch video