It has recently suffered its worst sectarian violence in years - a car bomb in Shi'ite Hizbollah territory in the Beirut suburbs and two at Sunni mosques in the northern city of Tripoli. Lebanese authorities accused Syria of involvement in the Tripoli attacks and intelligence officials fear there could be more to follow.

Syria could retaliate to an attack by America by lobbing missiles into Israel. Israel has vowed retaliation if it is attacked by Hizbollah, which is supporting Syria. That could draw Lebanon even further into the conflict. Then there's Iran. Iran is unlikely to respond by carrying out attacks from its soil but would get involved "through" Syria.

While Iran and Hizbollah support Syria's President Bashar al Assad, the Sunni opposition are supported and being armed by Gulf states such as Saudi Arabia and the United Arab Emirates who want to bring down Assad's regime. Into all this President Obama is considering firing his cruise missiles.

He may get away with a short, sharp slap, which will save face for America after the president warned Assad not to cross a "red line". But it could be more than chemical weapons sites that President Obama hits. He could open a Pandora's box of repercussions, which he may find hard to put a lid back on.

Major carriers including Emirates, the world’s biggest airline by international passenger traffic, rival Gulf carrier Etihad and British Airways are on alert as the United States threatens a potential strike on Syrian president Bashar al-Assad’s regime. A number of long-haul airlines fly through or close to Syrian air space to service other major destinations worldwide and link to key air traffic hubs in Europe such as Heathrow.

Tim Clark, president of Dubai-based Emirates and one of the industry’s most experienced figures, told The Sunday Telegraph that “contingency plans will be in place should anything happen” in Syria. Those plans could potentially involve re-routing aircraft away from the area, Mr Clark said, although he stressed operations will continue “as normal” unless there is a serious deterioration in the situation.

“We are always in a state of preparedness for anything like this and the operations group of the company will have all of this on watch; contingency plans will be in place should anything happen,” Mr Clark said. Airlines also face a threat from a potential spike in the oil price as a result of the growing tensions in the Middle East.

Syria expects a military attack "at any moment" after UN chemical weapons inspectors left the country, a security official has said. A UN team investigating an alleged gas attack crossed the Lebanese border on Saturday and have now arrived back in the Netherlands, heightening expectations of a possible US-led strike against President Bashar al Assad's forces.

A Syrian official told AFP: "We are expecting an attack at any moment. We are ready to retaliate at any moment." Syrian prime minister Wael al Halqi added: "The Syrian army is fully ready, its finger on the trigger to face any challenge or scenario that they want to carry out."

Russian President Vladimir Putin responded to the inspectors' departure by challenging the US to present evidence of chemical weapons use by the Assad regime to the UN Security Council. He said it would be "utter nonsense" for the Syrian government to use chemical weapons when it was winning the war, and urged US President Barack Obama not to attack Syrian forces.

So much for the element of surprise. Into his third year of dithering, two years after declaring Assad had to go, one year after drawing — then erasing — his own red line on chemical weapons, Barack Obama has been stirred to action. Or more accurately, shamed into action. Which is the worst possible reason. A president doesn’t commit soldiers to a war for which he has zero enthusiasm. Nor does one go to war for demonstration purposes.

The only defensible action would be an attack with a strategic purpose, a sustained campaign aimed at changing the balance of forces by removing the Syrian regime’s decisive military advantage — air power. Of Assad’s 20 air bases, notes retired General Jack Keane, six are primary. Attack them: the runways, the fighters, the helicopters, the fuel depots, the nearby command structures. Render them inoperable.

It’s rather shameful that while the British prime minister recalled Parliament to debate possible airstrikes — late Thursday, Parliament actually voted down British participation — Obama has made not a gesture in that direction.

Now that the British Parliament has voted against a military strike, the Obama administration is saying that it may take “unilateral action” against Syria. But what good would “a shot across Syria’s bow” actually do? A “limited strike” is not going to bring down the Assad regime and it is certainly not going to end the bloody civil war that has been raging inside Syria. Even if the US eventually removed Assad, the al-Qaeda affiliated rebels that would take power would almost certainly be even worse than Assad. Even in the midst of this bloody civil war, the rebels have taken the time and the effort to massacre entire Christian villages.

Why is Barack Obama so obsessed with helping such monsters? There is no good outcome in Syria. The Assad regime is absolutely horrible and the rebels are even worse. Why would we want the US military to get involved in such a mess? It isn’t as if it is even possible for the US military to resolve the conflict that is going on in that country. At the core, the Syrian civil war is about Sunni Islam vs Shia Islam. It is a conflict that goes back well over a thousand years.

Assad is Shiite, but the majority of Syrians are Sunni Muslims. Saudi Arabia and Qatar have been pouring billions of dollars into the conflict, because they would love to see the Assad regime eliminated and a Sunni government come to power in Syria. On the other side, Iran is absolutely determined to not allow that to happen. Saudi Arabia and Qatar have no problem with using Sunni terrorists (al-Qaeda) to achieve their political goals. And as a very important ally of the Saudis, the US has been spending a lot of money to train and equip the “rebels” in Syria.

But there was a problem. The Syrian government has actually been defeating the rebels. So something had to be done. If it could be made to look like the Assad regime was using chemical weapons that would give the US government the “moral justification” that it needed to intervene militarily on the side of the rebels. In essence, it would be a great excuse for the US to be able to go in and do the dirty work of the Saudis for them. Unfortunately for the Obama administration, the world is not buying it. In fact, people are seeing right through this charade.

The Arab League – which backed the war against Libya – has also said ‘no’ to an attack on Syria. After it was revealed that US claims that the Syrian government carried out the recent chemical weapons attack are wholly unsubstantiated, the US has become isolated.

World opinion is firmly against war. Congressman Grayson argues that nobody wants a war except the military-industrial complex.

The result is a devastating defeat for a Prime Minister who had been riding high until just a few days ago. Now he is left with his authority in tatters. This is a result with potentially enormous implications. It is no good Tory MPs who helped vote this down saying, as they are tonight, that this is not a personal blow to Cameron, rather that it is a good night for Parliament.

Perhaps it is good for Parliament's power, and the Executive has been put in its place (good), but there is no way round it in cold, hard, practical political terms. This is catastrophic for Cameron. It remains baffling. Why on earth did the Conservative leader and his aides not war-game this properly? Their strategy was predicated on the Labour leadership falling in to line behind intervention.

It was always a daft presumption, after Iraq and with public opinion so sceptical of more involvement in foreign wars. And Cameron's team overlooked or ignored that many Tory MPs were equally sceptical. A frantic Tory operation to shore up Cameron is underway tonight, with even rebels out there praising him for being a man of conviction. Well yes, he took a stand based on his conviction, and he lost, humiliatingly.

It was supposed to be a calculated snub to Britain, of course. With a few exceptions, in the past 100 years it’s become a rule of thumb that America no longer goes to war without Britain at its side. So the UK’s failure to follow the US into action over Syria inevitably stung in Washington, prompting Mr Kerry to cosy up to France.

But in reality Americans tend to mistrust the French even more than the British do. Famously, Americans refer to them as ‘cheese-eating surrender monkeys’.

In 1966, France pulled its forces out of NATO and kicked the US-led organisation out of its HQ at Fontainebleau. France earned its ‘surrender monkey’ moniker during the 2003 US invasion of Iraq. The French opposed a UN resolution authorising the invasion and, in retaliation, anti-French feeling swept across the US with public campaigns to boycott French goods.

President Barack Obama, meanwhile, said on Friday he has not made a final decision on a military strike against Syria. He sought to play down both the scope and duration of the anticipated punitive missile and bombing campaign.

“As you’ve seen, today we’ve released our unclassified assessment detailing with high confidence that the Syrian regime carried out a chemical weapons attack that killed well over a thousand people, including hundreds of children,” Obama said. The president said the use of the deadly weapons had violated international “norms” and that action was needed to prevent the further use of the arms.

A future military operation would not involve troops on the ground as part of a long-term campaign, Obama said. “But we are looking at the possibility of a limited, narrow act that would help make sure that not only Syria but others around the world understands that the international community cares about maintaining this chemical weapons ban and norm,” he said.

Syrian National Coalition spokesman Louay Safi called the decision a "failure of leadership" by the US. Government forces resumed shelling of opposition-held parts of Damascus as Mr Obama finished speaking on Saturday.

Congress is due to reconvene on 9 September, meaning any military operation would not happen until then.

Canal authority head Mohab Mamish said a "terrorist element" targeted a Panama-flagged vessel on Saturday, but it was undamaged. There were reports of two blasts, but details of the attack are unclear. Egypt's Sinai has been hit by a wave of violence since Islamist President Mohammed Morsi was ousted from power.

The unconfirmed reports said there were two explosions at 12:30 GMT on Saturday as the ship, Cosco Asia, passed through the waterway. "The situation was dealt with strictly by the armed forces," Admiral Mamish said in a statement. The Suez Canal - between Port Said and Suez - is a vital global trade route between the Red Sea and Mediterranean.

Archbishop Pietro Parolin, a 58-year-old Vatican diplomat, replaced Cardinal Tarcisio Bertone, 79, who is retiring. Cardinal Bertone, appointed by Francis' predecessor Pope Benedict, had been widely criticised over last year's so-called "Vatileaks" scandals.

Leaked documents revealed corruption and infighting at the Vatican. The secretary of state heads the Roman Curia, the central administration of the Catholic Church, and is the Pope's chief adviser.

Urgent calls were made to the White House last night soon after the government defeat amid claims by one Whitehall official that Britain had ‘handed back its deputy sheriff badge’. Chancellor George Osborne warned Britain must undertake ‘national soul-searching’ about its place in the world as Defence Secretary Philip Hammond warned the special relationship was now under ‘strain’.

Diplomatic experts also voiced deep concerns that the repercussions for Britain’s standing on the world stage would be long-lasting. The Henry Jackson Society said last night's Commons vote has damaged Britain's reputation as a major global power and also sent a worrying message to dictators, while the Royal United Services Institute (Rusi) said it was an embarrassment.

Former Liberal Democrat leader Lord Ashdown said the defeat in the Commons had left the UK a ‘hugely diminished country’. The influential Tory grassroots website Conservative Home said Mr Cameron had suffered 'the worst foreign policy defeat in modern times'. Mr Cameron had promised Mr Obama he would stand shoulder to shoulder with the US in taking military action against the Assad regime after the devastating chemical weapons attack in Damascus last week.

The Prime Minister recalled Parliament to stage an emergency vote to endorse UK involvement in missile strikes. But MPs voted by 272 votes to 285 to reject Mr Cameron’s motion backing British intervention in principle. It is the first time that Parliament has voted against the government on a matter of war and peace since 1782, and raises the prospect of the US having to go it alone.

A secret budget request obtained by The Washington Post from former NSA contractor Edward Snowden lumps Israel alongside US foes Iran and Cuba as “key targets” for US counterintelligence efforts. The document suggests Israel does not believe US assurances that its interests are aligned with Israel's on crucial issues such as Iran and peace talks with the Palestinians.

“To further safeguard our classified networks, we continue to strengthen insider threat detection capabilities across the Community,” reads the FY 2013 congressional budget justification for intelligence programs. “In addition, we are investing in target surveillance and offensive CI [counterintelligence] against key targets, such as China, Russia, Iran, Israel, Pakistan and Cuba.”

The White House and the Israeli Embassy did not respond to requests for comment.

The country’s oil ministry said production has slumped to an average of 300,000 barrels per day (b/d) in August, down by more than four-fifths from its peak after the overthrow of the Gaddafi regime two years ago. “Militia groups are behaving like terrorists, using control over oil as political leverage to extract concessions,” said Dr Elizabeth Stephens, head of political risk at insurers Jardine Lloyd Thompson.

Port closures and strikes have compounded the damage but the deeper story is the disintegration of political authority. Libya is the most extreme example of political mayhem around the world disrupting output and causing a chronic shortfall in oil supply. Production has slumped in Iraq, Nigeria, Iran, Yemen and Syria itself, each for different reasons.

This has cut daily global supply by 1.1 million over the past year to 92 million, explaining why Brent crude prices have remained stubbornly high despite the slump in Europe and China’s slowdown. To compound the problem, Libya’s oil is some of the highest quality produced in the Middle East and the kind preferred by European refiners. Jitters over Syria have already pushed Brent to $115, near levels that typically erode confidence and inflict serious economic damage.