The only thing the world can do, apparently, is watch. This, of course, does not mean that there is no interference. We know that several governments have sent their intelligence agents to the country to observe and sometimes to manipulate the situation. We also know that a number of illegal organizations are operating on the ground. Given this context, no nation can pretend it doesn't have a role in the ongoing violations of human rights and loss of life.
The problem is to discern the real intentions of a number of European powers, such as Germany, France and the United Kingdom, even though we know they are very much involved. We can at least suggest that Germany's main goal is to not provoke Iran further and the UK's objective is to cut the ties between Russia and Iran. As far as France is concerned, this country's essential aspiration is to take back its former zones of influence. The operation in Mali was only one example of this policy. However, these are just suppositions; it is not yet possible to be sure of these countries' game plans. For now, we mostly see ambiguities. On the one hand, they refuse to send weapons to the opposition groups, because they fear these weapons will end up in the hands of the radical Islamists; on the other, they insist that the Assad regime has to go. However, President Bashar al-Assad has no intention of leaving.
We have to admit that the US's position has been clear from the beginning of the crisis, since Washington has openly supported moderate opposition groups. This is a way of saying that the US is as opposed to the radical groups as it is opposed to the Assad regime. The US is expecting the fall of al-Assad, but it also wants his regime to be replaced by a moderate one.
Russia can no longer dissimulate its uneasiness about the evolution of the situation in Syria. Moscow, too, is disturbed by the growing influence of radical Islamist movements. It seems that the danger these groups represent is the only subject on which every great power agrees. However, these radical groups clearly enjoy some kind of support from third actors. Probably the great powers that are fighting against each other in Syria are somehow using these organizations.
Russia would prefer that the opposition groups come to an agreement with al-Assad. Nevertheless, the opposition groups have announced that they will not negotiate unless al-Assad orders his troops to put an end to the armed operations. But they don't say that they, too, will lay down their weapons.
What is important is that everyone has finally understood that the resolution of the conflict will not be possible without Russia's will. The fact that Russia is becoming more and more involved in the crisis will reduce Iran's weight, and only then will the great powers come to an agreement about a comprehensive resolution.
A critical development has recently occurred proving Russian determination to play a bigger role in the Syrian crisis: Moscow has proposed cooperating with the Arab League in order to launch direct talks between the Syrian regime and the opponents. The fact that major Arab countries have come to an agreement with Russia about a roadmap for the resolution means Iran's clout over Syria is diminishing. Under these circumstances, it is irrelevant to ask who is supporting al-Assad and who is going to fight against the radical groups.