Syria’s armed forces rely on Russia for tanks, artillery, armoured personnel carriers and strike aircraft. The Stockholm International Peace Research Institute calculates that Russia alone provided almost half of Syria’s military imports between 2006 and 2010.
While Russia supplies weapons, Iran has intervened directly, sending thousands of Hizbollah fighters from Lebanon to serve alongside Syria’s army.
An oil embargo and other sanctions have succeeded in choking off Mr Assad’s sources of revenue. Last year, his central bank was believed to be spending its reserves at a rate of $1 billion per month, with only $3 or $4 billion left by December.
Iran probably came to rescue and bailed out Mr Assad.
So whether it comes to weapons, cash or boots on the ground, either Russia or Iran will actually deliver. And they do not need to worry about parliamentary votes, Congressional support or, indeed, public opinion.
Compare and contrast the help given to the opposition by America, Britain, the other Western powers and the Arab League. Do they have a shared objective? In theory, they all want Mr Assad to go; in reality, David Cameron and President Obama have been at pains to say that deterring the use of poison gas – not toppling the regime – would be the goal of any military campaign.
Can they actually deliver firepower? Arab countries like Qatar and Saudi Arabia are willing to supply weapons, but neither is a big military power, able to provide advanced military capability. Meanwhile, the West has dropped its arms embargo, but without summoning the resolve to actually supply weapons.
As for money, Qatar and Saudi Arabia can deliver large sums, but the West prefers to focus its help on humanitarian aid. The obvious conclusion is that authoritarian regimes are much better allies than Western democracies.
The one factor that could have changed that – a series of American-led air and missile strikes on the regime’s nerve centres – now seems in doubt. If, following Britain’s abdication, Mr Obama does not deliver, then the field will be left clear for the Russia-Iran-Assad axis.
They may not be strong enough to achieve outright victory, but they will be able to preserve the regime in its Damascus stronghold and give Mr Assad enough confidence to reject a negotiated settlement. That would be a formula for endless war.