As Nato's mandate officially ends in Libya, Channel 4 News looks at why the UN has not sanctioned the use of force against President Assad's regime in Syria.

President Assad, UN flag, Colonel Gaddafi (Getty, Reuters)

In a strongly worded statement over the weekend, the Syrian President Bashar al-Assad warned of an "earthquake" if western powers sought to interfere with his government. It is the latest threat that the president has issued hinting at the wider impact of outside intervention.

Assad is facing increasing pressure to move aside, as his regime attracts strong international criticism for his harsh crackdown on pro-democracy protests. The protests have also dented his government's legitimacy around the world.

But experts on the Middle East say Assad's warnings are not without foundation. Syria's sensitive geopolitical position means it is more difficult for the UN or Nato to take action against it. Countries such as Iraq, Lebanon, Jordan and crucially Israel, share its borders and Syria is currently in territorial or border disputes with at least two of those nations.

Even China and Iran have called on Assad to reform Jane Kinninmont

Jane Kinninmont, senior research fellow for the Middle East and North Africa at the think tank Chatham House, told Channel 4 News in the event of action against Assad, the potential for Syria's instability to spill over to the rest of the region is great: "Syria certainly has scope to destabilise Lebanon, although ironically this is a little harder to do now that a pro-Syrian coalition is in power there; if Lebanon still had an anti-Syrian government we would probably have seen it paralysed by now.

"Syria could also try to stoke tensions in Turkey through Kurdish groups there. The security of its borders with Israel and Iraq could also be relaxed to allow militants through. Having said all that, any of these courses of action would be highly risky and would make Syria new enemies."

"Bashar Assad had some success in the past in branding himself a reformer, but the heavy-handed repression he's overseen this year has greatly damaged his legitimacy and has swelled the ranks of the opposition.

Technically, there could be the potential for the UN to take action under its "responsibility to protect", as it was in Libya, but analysts think this would be looked upon with suspicion by Russia and China.

Syria and surrounding region

Disunited opposition?

Although Libya's opposition was able to coalesce long enough to overthrow Colonel Gaddafi, some experts believe groups opposed to the Assad regime are too fragmented to provide a credible and coherent voice of dissent.

There has also been a lack of unity over whether to back a no-fly zone, although this may be changing. Jane Kinninmont says: "Originally the opposition groups said the uprising should involve no violence, no foreign intervention and no sectarianism. They know foreign intervention could backfire in Syria, where many people are ready to believe that the west and Israel are conspiring against them. However, as the deaths mount, there are likely to be more calls for foreign protection.

"Since September, several opposition groups have called for a no-fly zone. Some opposition members have argued that a no-fly zone could help encourage more soldiers to defect from the Syrian army, by providing a safe haven for defectors along the border with Turkey."

Caught in the middle

Despite the voices of dissent, Assad does have supporters, although it is hard to establish exactly how much backing he enjoys. Certainly, in the past his foreign policy has been popular.

Before action against the Gaddafi regime was rubber-stamped, there had to be wider regional support which finally came in the form of backing from the Arab League.

There is not going to be the sort of intervention there was in Libya Prof Mats Berdal

And while there are many people calling for the president to step down, there is likely to be a sizeable portion of Syrians who find themselves neither supporting Assad nor backing him.

Jane Kinninmont from Chatham House said: "There are a lot of people in Syria who find themselves caught in the middle; they dislike the Assad regime and the Ba'ath Party but they do not want to see foreign-backed regime change."

And Ms Kinninmont said although there has been support internationally from sympathetic nations, this appears to be waning: "Even China and Iran have called on Assad to reform. China would be likely to block any attempt at an intervention through the UN security council, but it is not backing Assad uncritically.

"Saudi Arabia's opposition to Assad is important here. As the biggest oil exporter in the world, Saudi Arabia is a vital trading partner for an increasingly oil-hungry China, so China will not want to be seen as backing Syria and Iran decisively and uncritically."

What are the options?

If, as some analysts think, there is little likelihood of UN action against the Assad regime, are there alternatives which will bring to an end months of bloody clashes between pro-democracy protestors and government forces?

Jane Kinninmont's gloomy summary is that "basically all of the current options are bad".

But Professor Mats Berdal from King's College, University of London, told Channel 4 News there is something that the international community can do to try and prevent the situation descending into another Rwanda: "The international community remains deeply divided about the rights and wrongs of humanitarian intervention and many, especially from the developing world, are deeply sceptical about the notion of a 'responsibility to protect'.

"For a variety of reasons, there is not going to be the sort of intervention there was in Libya. It is all the more important therefore that we focus on the reporting of what is going on in Syria, that we draw attention to the violations of human rights that are being committed daily.

"Moral pressure may, or so we must hope, eventually induce a change of behaviour on the part of the government in Damascus and/or of its allies on the UN Security Council - China and Russia".

More on this story