The calls for international, by which it is essentially meant US, intervention in Syria raise some important questions about the relationship between sovereign states and the global community.
There are, of course, some recent precedents for outside intervention in the affairs of nation states to bring about a change of regime or even to create a new national entity out of one region of the original country.
So in the 1990s NATO bombing forced Serbia to surrender its province of Kosovo which had an Albanian majority with a still significant Serbian minority population. Kosovo was then recognised as a new national entity by most of the international community. And it was a NATO-sponsored no-fly zone over Libya that largely resulted in the collapse of Muammar Gaddafi's rule and the takeover by a new government.
There was, however, no such outside support for Chechnya's efforts to separate from the Russian Federation in the 1990s or the struggle by the Tamils over many years (now seemingly ended) to split off from the rest of Sri Lanka.
Throughout history there has been a great deal of chance involved in whether rebel forces have received the outside support that many need to secede from the existing regime or to overthrow it altogether. If the Confederacy had been able to get significant international recognition in the early 1860s it might have been able to put more pressure on Abraham Lincoln's administration for a negotiated settlement. But its slave-based economy was not only the major factor in sparking the conflict. It was also a powerful disincentive for the nations of Europe, particularly England, to recognise its existence as a legal entity.
But back to Syria. There can hardly be any dispute the Assad regime is an extremely unattractive one and has engaged in brutal repression of a rebellion in some regions of the country. Is it, however, less attractive than the governments of, for example, Iran, Yemen or Saudi Arabia? To a large extent the conflict in Syria is a tribal one, between the ruling Alawites and the rebel Sunnis. The rebels obviously have access to weapons from outside the country and it can be assumed they are financed, at least in part, by their Sunni colleagues in Saudi Arabia.
But recall Afghanistan in the 80s. The US provided considerable support for the mujahedin who eventually toppled the government and forced the withdrawal of the Russian troops that had supported it. This led ultimately, however, to the rise of the Taliban and the use of Afghanistan as a training ground for terrorists. In a final irony the US was then compelled to intervene in a fashion reminiscent of the Russians in the 80s. There is no evidence the Syrian rebels have any interest in a more democratic and representative administration than that of Assad. Nor is there any evidence they would be more sympathetic to US interests in the Middle East, including the long-term goal of encouraging some kind of negotiated settlement between Israel and the Palestinians.
All of this does not make it any easier to watch the scenes of carnage that regularly emerge in reports from inside Syria.
But there are a number of regimes around the world that repress their own people in the most brutal fashion. How is it to be determined which of them will be left without physical interference (as opposed to diplomatic condemnation) and which will be the subject of military intervention? Many would say that the mass killings in Cambodia in the 70s and Rwanda in the 90s would justify intervention from outside. These are obviously extreme examples but they still raise the question of when the conduct of a sovereign state towards its own citizens justifies military action by an international organisation or by a neighbouring country.
In the days before television coverage of conflicts these questions were largely academic. But graphic images of the results of aerial bombardment and tank attacks has placed much greater pressure of international bodies and a great power like the US to intervene in the internal affairs of individual nations. The problem is that no one has so far successfully formulated a set of principles that would suggest when the line has been crossed that would authorise such intervention.
The cautious approach so far of Barack Obama in relation to the Syrian problem suggests that he at least is aware that this is a very difficult line to draw.