Business Opinion: Denis O'Brien has clearly been reading his Von Clausewitz. The long-dead Prussian general - whose treatise On War is seen as the first real management book - wrote extensively on the use of surprise to sow confusion amongst your enemies as to your real intentions.

O'Brien's decision last week to break cover about his stakebuilding in Independent News & Media has certainly got the Dublin market scratching its collective head. The upper echelons at Independent News & Media are no doubt equally puzzled, and, one suspects, more than a little concerned.

The only thing that observers appear able to agree on is that O'Brien wants his interest in IN&M out in the open. Two factors point to this; the holding of the shares in his own name rather than through some sort of investment vehicle, and, more pertinently, the decision to disclose his interest once he passed the 3 per cent threshold rather than wait until he got to 5 per cent.

After that, commentators are divided into two camps. There are those who think O'Brien is merely rattling Sir Anthony O'Reilly's cage and those who think this stake is the first stage in a battle for control of IN&M.

Supporters of the first - and it must be said the simplest - explanation point to O'Brien's decision to announce at the 3 per cent threshold. If he was up to something more clandestine, he would have kept his powder dry for longer, i.e. until he passed 5 per cent.

Another reason for favouring the first school of thought is that there are no shortage of reasons why O'Brien might spend up to €56 million just to annoy O'Reilly. Relations between the two are said to be poor, with O'Brien still resentful of the way O'Reilly trumped him in the battle for Eircom. In addition, he is said to be unhappy with the treatment he receives from the O'Reilly-controlled press.

The problem with this analysis is that it paints O'Brien as some sort of impetuous mad man preoccupied with seeking revenge for perceived affronts. This does not really square with what we know of him, although he is without a doubt hot blooded.

However, the alternative school of thought is hard to digest. The biggest obstacle to believing that O'Brien is up to something more than just winding up O'Reilly is the seeming impossibility of what this suggests; a tilt at IN&M.

O'Reilly's position at IN&M is thought to be impregnable. He controls 28 per cent of the group and has had 33 years in which to organise a board, the loyalty of which is unquestioned.

O'Brien's problem would not be raising the money to buy IN&M if he wished, but actually getting the business into play in the first place.

He is an extremely wealthy man and likely to get ever richer should he float his Caribbean mobile interests, as expected. He has shown, as in the case of his recent bid for Meteor, that he has no difficulty finding backers with deep pockets.

In terms of how he might go about tackling IN&M, there are some superficial comparisons with the recent take private of Jurys Doyle, where Seán Dunne built up a large stake in the hotel business and ultimately engineered a situation in which he acquired some prime assets. The Doyle family, who thought themselves pretty well entrenched, were forced to pay up to take the rest of the business private.

But the comparison does not really hold up. Jurys was effectively in play before Dunne got involved. Another group of investors, Precinct, had already decided to have a go at the company on the simple premise that the share price did not reflect the value of the property assets.

There is no such mismatch at IN&M. The shares are not particularly undervalued and the balance sheet is not particularly under geared. There may be a certain fashion for breaking up media groups, but there is no compelling logic for asset stripping IN&M.

If O'Brien's intention is to build a stake in IN&M of sufficient size that he can force it to put itself on the block, then he can look forward to the fight of his life. It's hard to see it.

Assuming then that O'Brien is not a mad man bent on revenge, and nor does he want to engage in trench warfare with O'Reilly, then what is he up to?

The obvious answer to this is that he thinks something is going to happen at IN&M shortly and he wants to be at the party. In the meantime, he is happy to be an investor, particularly given the fillip to the share price that accompanied his arrival on the share register.

Possible triggers are succession issues at IN&M - O'Reilly is 70 in May - and/or the prospect of some other media group or private equity group having a pop at them. Perhaps O'Brien is happy to wait, and if he causes his old enemy a few sleepless nights into the bargain, all the better.

In the meantime, we watch with interest.