Syria: What lies ahead

Syrian army soldiers are seen deployed in the Jobar neighbourhood of Damascus, Syria. Photo / AP

What is the objective?

There are two main options. America and its allies could punish President Bashar al-Assad for using chemical weapons and deter their future use. Or they might go further and try to destroy his regime. The former would be a relatively brief campaign against important military targets; the latter a sustained, Kosovo-style operation lasting weeks or months. At present, the less ambitious choice seems more likely. The fact that Britain is suggesting action in a week or so suggests the aim will be punishment, not regime change.

What about the United Nations inspectors?

A 20-strong team of UN experts arrived in Damascus over a week ago charged with discovering whether chemical weapons had been used in earlier incidents. Yesterday, they were allowed to visit the sites of last Thursday's attacks, although snipers shot at them along the way. Their mandate restricts them to finding out whether chemical weapons were used - which is no longer disputed - not who was responsible. The "who did it" question is central. Unfortunately, the inspectors' mandate will prevent them from offering a conclusive answer.

So will the experts achieve anything useful?

Possibly. They might be able to establish which chemical agents were used. The regime is known to possess stockpiles of mustard, sarin and VX nerve gas. If the UN finds that any of these were used, this might implicitly point the finger. But any definitive findings are unlikely.

What could be the targets for any allied air strikes?

It will depend on the objective. If the aim is punishment, then all the strikes are likely to be conducted at long range. Warships and submarines in the Mediterranean will launch Tomahawk cruise missiles; bombers will fire "stand off" missiles. No aircraft will fly over Syria, removing the need to suppress air defences. The targets will probably be important military installations such as arms dumps, air bases and communications centres. The campaign would probably be quite brief. If, however, America and its allies choose the Kosovo option and decide to topple Assad by changing the balance of the civil war, a far wider range of targets will need to be hit. They will start by destroying air defences - described by one RAF source as "highly capable and quite frightening" - and then move on to military bases and sites connected with the regime, such as key government ministries.

What about chemical weapons stockpiles?

They would be possible targets for either option. However, unless the attacks totally vaporise the weapons, there would be a risk of dangerous leaks. Stockpiles could also be left vulnerable to plunder by rebels and terrorist groups, including al-Qaeda.What forces are available?The US Sixth Fleet in the Mediterranean already has four cruise missile-firing destroyers on standby. In the Gulf, the Fifth Fleet has two carrier battlegroups. Each nuclear-powered aircraft carrier has about 70 fighters. America also has air bases with F-16 fighters in Turkey and Jordan.

What could Britain contribute?

The Royal Navy's rapid reaction force is already on long-planned exercises in the Mediterranean. The 10-vessel taskforce, currently off the Albanian coast, includes the helicopter carrier HMS Illustrious and two Type-23 frigates. There are also seven support ships. But none of these vessels can fire land-attack missiles or launch strike aircraft. So the main British contribution would probably be cruise missiles fired from a submarine. HMS Tireless, a Trafalgar-class submarine armed with cruise missiles, was reported in Gibraltar at the weekend. In addition, RAF Akrotiri in Cyprus is ideally positioned for air strikes on Syria. The RAF says it has no warplanes in the region at present, but America could ask to use this base.

What are the risks?

There is very little risk to British and American forces firing cruise missiles. These would be long-range "stand-off" attacks. The first big risk would be civilian casualties inside Syria: air strikes are rarely as clinical as commanders claim. The second possibility is that Assad could retaliate. Syria has one of the largest arsenals of ballistic missiles in the Middle East. Its Scud missiles could carry chemical warheads and have a range of several hundred kilometres. Turkey, Jordan, Cyprus and Israel would all be possible targets.

Q: So what happens next?

America, Britain and France will probably place a draft resolution before the UN Security Council condemning the recent chemical weapons attacks, blaming the regime and authorising the use of force. Russia and China will cast their vetoes. America and its allies would then invoke the "responsibility to protect", a doctrine adopted by the UN in 2005 allowing member states to intervene to "protect populations from genocide, war crimes, ethnic cleansing and crimes against humanity". They will use this as their legal basis for action, even if the Security Council declines to pass a resolution. The diplomatic wrangling will probably take some time.