On the face of it, President Saddam Hussein's rule is as monolithic as the opposition is divided. There is total popular support for the man and his works.
But that is only the facade, induced by the terror he inspires not only in the people at large but among his own followers, from the lowliest to the highest. The almost magic aura of invulnerability that surrounds him is what, above all, holds the whole despotic system together. Killing him would almost certainly bring the whole regime down.
It is not, apparently, an Anglo-US war aim to "get" President Saddam. Whether sincere or not, that is certainly recognition of an inescapable reality. "How", aptly asked an Arab newspaper the other day, "can one eliminate a man who doesn't shake anyone's hand until his fingernails have been checked for poison, doesn't use mobile phones to avoid being traced, travels incognito, holds his meetings in secret locations, doesn't appear in public and moves about in 10 identical convoys, so no one can see the vehicle he is in?"
But his personal ascendancy would be nothing without his elite military and security apparatus.
All Iraqi regimes have built their power on the sectarian solidarity of the Sunni Muslim minority, but none has taken this to the extremes that President Saddam has. He relies not merely on a minority, but on a small minority of a minority; and the more mistrustful, with time, he has become, the more he has concentrated power within his immediate family, notably his sons Udai and Qusai.
The 80,000-strong Republican Guards are drawn mainly from the Sunni community; far better equipped and paid than the dispirited regular army, their main purpose is to defend the regime. Above them are the Special Republic Guards (SRG) and the Special Security Organisation (SSO); their only task is to protect Saddam and his family.
The 6,000-strong SRG consists of 14 brigades, five of which are always around him. The 800-strong SSO engage in surveillance operations in close collaboration with it.
"You will find the SSO inside Saddam's palaces", said an Iraqi opposition expert, "the SRG outside them. But, typically, the rank and file of each is forbidden even to talk to the other."
All their members come from his hometown of Tikrit and its immediate environs. Both groups are controlled by Qusai.
If sustained aerial bombardment did real damage to these key institutions, it would undoubtedly put the regime in danger. That is why, whenever the US and Britain have been on the point of attacking, President Saddam has dispersed his Republican Guards from their main bases in and around the capital. This time, the attack came so swiftly he may not have managed the dispersal.
The dangers for Mr Saddam are threefold. First, though he himself is almost certain to survive any onslaught, his apparatus might be so badly mauled that the people, perceiving weakness and confusion, rise in insurrection.
The second is the more organised threat of Iraqi opposition groups. On paper there are no fewer than 70 organisations, some of them little more than individuals or small cliques, in the Iraqi opposition. Most of them are based in Arab states or the West.
Their profusion is one measure of how notoriously divided that opposition is, how hard it must strive to achieve the minimal community of purpose deemed necessary to bring the tyrant down and keep the country in one piece.
One opposition section speaks essentially for the orthodox Sunni Muslims of central Iraq, who, though comprising 15 per cent of the population, dominate the country's political life. Another speaks for the Shia Muslims of the south; at 60 per cent they are by far the largest single community. And then there are the Kurds of the north.
There has always been friction between these communities, but it is one of Mr Saddam's successes that he has exported into their ranks much of the sectarianism on which he relies.
Reinforcing these indigenous tensions is the fact that all parties look to rival foreign sponsors, Arab or further afield. The communists are perhaps the only important party that can claim to be truly multi-ethnic.
Historically the least visible but most dedicated opposition has come from the Shia. Owing to the nature of Shia society, plus the rise of Khomeini-style fundamentalism, the traditional clergy or radical Islamist groups have been to the fore in this underground struggle.
The Kurds have a long tradition of armed rebellion. Since the Gulf war they have been the only opposition that remains firmly inside Iraq and - under Western aerial protection - falls outside Baghdad's control. But clan and regional rivalries have sparked bouts of virtual civil war between the two main Kurdish parties, Mr Massoud Barzani's Kurdistan Democratic Party and Mr Jalal Talabani's Patriotic Union of Kurdistan.
The most promising effort to unite these disparate forces has come from the Iraqi National Congress, the brainchild of Dr Ahmad Chalabi, which seeks a "democratic and pluralist" Iraq. It first set itself up in "liberated" Kurdistan, but the inter-Kurdish strife contributed mightily to its decline. The Kurds are deeply reluctant to sacrifice the relative freedom and security they have achieved for the uncertainties of a new adventure to oust Saddam.
For all their divisions, much of the opposition acknowledge that they need outside, especially US, support. So the Clinton administration's recent conversion to the idea of joining forces with the opposition to topple President Saddam opens new possibilities.
The third and final danger comes from within. Along with a coup or an uprising, assassination, or some convulsion within the House of Saddam, is a third possible way for Mr Saddam to go.
True, the normal response of insiders under threat is to rally round their chief more loyally than ever, knowing that if he goes, they go with him. But in a ruling elite as murderous as Saddam's there is surely someone who sooner or later is going to raise his hand against the Monster of Monsters on whom they all utterly depend, but whom they also fear and loathe.