After the second night of bombing, NATO planners in Brussels are busy analysing the damage sustained by the Yugoslav military. Much of this damage assessment will remain a military secret. But, even at this early stage, it is possible to draw some preliminary conclusions about NATO's real aims and the Yugoslav response.

The first wave of air attacks was both broader and much more powerful than anticipated. Initially, NATO plans called for the destruction of Yugoslavia's integrated air defence systems. This task was meant to be accomplished with cruise missiles, in order to minimise Yugoslavia's ability to hit at Alliance aircraft. Cruise missiles were duly fired (and, for the first time, by Britain, as well as the United States). Yet the attack was swiftly followed by waves of manned aircraft.

Furthermore, although the list of targets hit during the first night of the attack included the predictable military communication and radar facilities, NATO also hit at munitions factories and military barracks throughout Yugoslavia. The conclusion is that the Alliance is much more confident about its ability to control the air space, but also that NATO feels that time is not on its side; the military wants to inflict the largest amount of damage in the shortest period of time.

Just as interesting is the response of Slobodan Milosevic, the Yugoslav dictator, to these strikes. Contrary to the original predictions, he did not use his extensive air defence network, which includes some sophisticated Russian-made surface-to-air missiles. Indeed, in most cases the Yugoslav radar systems were not even switched on to "lock" on incoming Western aircraft, a necessary first step before missiles are fired.

The Yugoslav military was not taken by surprise: if every media network around the world knew when the bombing was scheduled to start, so did Slobodan Milosevic. The assumption is, therefore, that the authorities in Belgrade made a conscious decision not to use their air defence at this stage. And the reasons for such a decision are quite easy to imagine. Sophisticated NATO systems can detect and destroy any radar which locks on aircraft. Milosevic wants to preserve as much as possible of his military assets because he is planning for a long war, rather than a short burst of activity.

Protecting these assets also serves a psychological purpose: as long as some radar remains potentially active, NATO cannot be sure that it has obtained complete control over the skies. Belgrade may be planning to throw in most of its resources at a later stage, in the hope that this will have a lethal effect just when the West's media and public opinion get bored with the action, or when the doubts about the purpose of the operation multiply.

And, while the air strikes continue, Milosevic has moved to consolidate his iron grip inside the country. One of his first moves was to close the sole independent radio station broadcasting in Belgrade. Most of the foreign journalists have been kicked out of the country, and Milosevic has also proclaimed a "state of war". The proclamation gives the Yugoslav President extensive powers over the country, which he may want to use in order to silence Montenegro, a component part of Yugoslavia, which is now ruled by pro-western leaders.

The official media have already started hinting at the presence of "foreign agents" in the country, a prelude to a political purge. So, despite all the official claims of invincibility, it is clear that Milosevic is fearful of his population's reaction. NATO planners always assumed that, the moment the air strikes began, Belgrade's official media would start claiming massive civilian casualties. The claims duly came last night, but they were rather modest: the Yugoslav authorities allege only 10 dead civilians.

The explanation for this unexpected moderation may be that Milosevic has realised that the propaganda value which he may derive from claims of great civilian casualties has to be set against the alarm which such claims may sow in the civilian population. There are other indications as well that the government's grip on the country is less than perfect: the authorities appear to be failing in the recruitment of reservists, particularly in the towns.

Yugoslavia has suffered considerable damage in the last two days. But, true to form, President Milosevic is determined to remain defiant. And he is no doubt drawing some courage from the fact that world media have already started asking awkward questions about the purpose of the operation, while Russia is pressing for a new political initiative.

All in all, the Yugoslav dictator has adopted the hedgehog approach: he curled up, gave nothing away and is now waiting for the storm to pass. NATO's military alternatives are not getting any easier.

Jonathan Eyal is director of studies at the Royal United Services Institute in London