Britain must be prepared to go to war if it wants to end the conflict in Syria and keep chemical weapons out of the hands of al Qaeda, the outgoing head of the armed forces has warned.
General Sir David Richards, who steps down today as Chief of the Defence Staff, said that if the West wanted to see an end to President Bashar al Assad's regime it would have to step in as in it did to end the Gaddafi regime in Libya.
He also warned that if the regime suddenly collapsed then Britain "would have to act" to prevent chemical weapons falling into the hands of terror groups.
His comment were backed by the Defence Secretary, Philip Hammond, who said that no option was being taken off the table when it came to Syria.
The 61-year-old general said there was "a lack of international consensus" over how to act over Syria but a shared reluctance to see Western boots on the ground.
"If you wanted to have the material impact on the Syrian regime's calculations that some people seek, a no-fly zone per se is insufficient.
"You have to be able, as we did successfully in Libya, to hit ground targets.
"You have to establish a ground control zone. You have to take out their air defences. You also have to make sure they can't manoeuvre - which means you have to take out their tanks, and their armoured personnel carriers and all the other things that are actually doing the damage.
"If you want to have the material effect that people seek you have to be able to hit ground targets and so you would be going to war if that is what you want to do."
Mr Hammond responded by saying: "I think it's very unlikely that we would see boots on the ground (in Syria), but we must never take any of the options off the table."
Gen Richards also said that British forces could also be sent to the country to prevent chemical weapons falling into the wrong hands.
"The risk of terrorism is becoming more and more dominant in our strategic vision for what we might do in Syria.
"If that risk develops, we would almost certainly have to act to mitigate it and we are ready to do so. I think it is a very big question. If we saw chemical weapons proliferate as a result of what is happening in Syria then we would have to act."
He said in an interview with The Sun: "Some could characterise that, even though it might be for a limited period, as a war."
It comes after independent reviewer of terrorism laws David Anderson QC warned in a report that Syria is the new hotbed for terror.
He cautioned that it could soon become more significant for groups such as al Qaeda than Afghanistan and the lawless tribal areas of Pakistan.
And last week the Intelligence and Security Committee (ISC), warned Syria's arsenal of chemical weapons could fall into the hands of al Qaeda militants if Mr Assad was toppled with potentially "catastrophic" consequences.
Tensions over Syria dominated the G8 gathering in Northern Ireland last month, which took place in the wake of an announcement by US President Barack Obama that the US was ready to arm the rebels despite Moscow's opposition.
Prime Minister David Cameron said Mr Assad had "blood on his hands" and insisted it was "unthinkable" the dictator could play any part in the nation's future.
The conflict, which is into its second year, has now claimed 100,000 lives, according to United Nations estimates.
General Richards steps down after a career of more than 40 years in the Army.