Syria analysis: Why air power alone won't beat IS
This is a significant moment in the US-led campaign to "degrade and destroy" the so-called Islamic State (IS).
The extension of the military campaign from Iraq to embattled Syria underscores the essential need to combat the organisation in both countries. IS has in any case made their mutual border largely meaningless.
The fact too that according to the Americans a number of Arab states were involved in the mission underscores that this is not like the last US foray into Iraq.
In some senses it resembles much more the coalition that came together to liberate Kuwait, though the challenge is very different, and the campaign is likely to last much, much longer.
The US and its allies have been collecting intelligence data on IS targets for some time. The Syrian leg of this campaign was always going to begin in high gear and high tempo.
The fact that they involved aircraft, armed drones and sea-launched cruise missiles indicates this was the most intensive night of the US-led air campaign so far.
This is not, though, a knock-out blow but the strategic aim is clearly to push IS off balance by striking at its leadership and support apparatus and hopefully - the Pentagon would say - to keep it there.
So far this campaign both in Iraq and Syria has rolled out as most analysts and the White House itself would have predicted.
The question now is not so much what comes next - air strikes are likely to settle down into a regular pattern with bursts of more intense activity related to developments on the ground.
The real questions are: can the other elements of the US strategy be rolled out equally effectively? Can the conditions for an IS defeat be established on the ground? And to what extent can IS itself fight back?
On the ground
For the US and its allies may well have acted, as they see it, out of necessity but they have embarked upon an unpredictable and uncertain course. This is because the external military element in this campaign - air power - is only part of a much broader range of forces that need to be coordinated.
Take the case of Iraq. Here US air power does seem to have halted the advance of IS, especially into Kurdish-held areas of the north. But the US air activity has not yet really begun to evict IS from Iraqi soil. That is crucially going to depend upon two factors.
Firstly, the availability of a well-trained and motivated force on the ground to fight IS toe to toe and gain territory. Kurdish Peshmerga forces are being equipped and trained. The US is attempting to restore the credibility of at least some of the Iraqi military, which originally crumbled in the face of the IS onslaught. But all this will take time.
The second crucial factor is political. That is why the US refused help to Iraq until a more inclusive government was in place, though establishing better governance in the country so that all groups feel part of the Iraqi state - whatever that means - is again going to take considerable time.
But this in a sense is the key. A versatile formation like IS can in a sense be defeated militarily but the likelihood is that it will simply morph into another phenomenon and reappear at a later date.
Conditions need to be created so that Sunni tribes turn away from it due to its brutality and constricted vision - in other words military factors are employed to help to defeat IS from within. The political battle is every bit as important as the military.
And this is where the policy of the US and its allies begins to look on softer ground. Even if this joint political-military struggle can be won in Iraq - where there is at least a recognised government - applying the same methods in Syria are an altogether different prospect.
Here it is going to take months to train up effective local forces amongst the moderate opposition and many analysts wonder even then if they will be a match for the zealots of the jihadist movement. There is no government in Syria accepted by the West, and, worse, there is no real political plan for the country's future.
Circumstances also change. IS has a role in this fight. It has so far shown itself to be adaptable and capable of pursuing strategic thinking of its own. So how might it respond to the US-led campaign?
It can do a number of things. By shifting its offensive against the Kurds from Iraq to Syria, it underscored the disruption that it can cause, sending a huge wave of refugees flooding across the Syria-Turkish frontier.
It is calling upon a kind of confederacy of Islamist extremists to attack Westerners both abroad and in their own capitals. The seizure of a French national in Algeria seems to be the first fruit of this policy. So IS has options in this battle which will make the task of the US and its allies harder.
But above all it should be remembered that, as many analysts are noting, this struggle is all part of a wider civil war within the Muslim and Arab world that pits to some extent cross-cutting coalitions of Sunni states against Shia; Iran against the Arab states; and those seeking to maintain the status quo against those who would shatter it. And whatever the outcome, in civil wars, some would say, there are no clear victors.