The amusing conservatives who hector one another on Rupert Murdoch�s Fox News were shouting a little louder yesterday morning.

The amusing conservatives who hector one another on Rupert Murdoch's Fox News were shouting a little louder yesterday morning. Barack Obama's overseas trip had taken him to Iraq and to what appeared, alarmingly, to be a highly cordial reception.

According to the tape, Mr Obama was sitting at Prime Minister Nouri al-Maliki's right hand. In fact, he was sitting in the big chair the Iraqis would normally offer to President Bush. The guy is just a candidate, said the talking heads, but here he was being treated like some sort of hyper-assured leader-in-waiting.

It is not often that Fox does Mr Obama any favours, even unwitting favours. But what did the pundits think was the purpose of a 10-day trip to foreign parts for a candidate perceived as being weak on foreign affairs? An apparent endorsement from Mr al-Maliki in a Der Spiegel interview was the icing on the cake. Leader-in-waiting: tell it to the heartland. That should break Mr Obama's heart.

This is not to say that the candidate has lacked serious purposes. Showing Americans that he, unlike a certain predecessor, can forge a working relationship with Europe is one. Interestingly (at least for Britain), the big speech intended to do that job will be delivered in Germany tomorrow.

Yesterday's arrival in Israel also had clear domestic function. No American candidate - and these days, apparently, no British Prime Minister - can afford to appear less than staunch in his unwavering, even unquestioning, devotion to a friendship that some of us find troubling.

Those appointments could be described as lesser stops on the itinerary, however. Gordon Brown used his own visit to Israel to make a symbolic gesture with regard to Iran, and Mr Obama will no doubt do the same. Britain, European or not, meanwhile, does not pause often over its transatlantic alliances. For the larger world, Iraq and Afghanistan are the policy issues. Both men have made the social calls.

Mr Obama has appeared to waver somewhat recently in his commitment to withdraw American troops from the former country within 16 months of his inauguration. There has been a suspicion that, with the nomination locked up, promises might have become a little less solemn. Those who suspect it have been Liberal Democrats, incidentally, and they are not yet reassured.

Mr Brown is a little further along that political cycle. True, he never said that he would extricate Britain from Tony Blair's war, but he allowed plenty of people to think it. Yesterday he was informing the Commons that as Iraqi forces become more expert, British troops will leave. One day. No "artificial deadlines", of course: no-one knows the identity of the next US President, after all.

Still, finally, inch by inch, we seem - but never speak too soon - to be heading for the exits. Judgment should be reserved until the American "surge", deploying the troops Donald Rumsfeld refused to deploy to begin with, has abated. Unlike Mr Bush, no-one these days declares victory in Iraq. But only the Republican candidate, John McCain, still has an appetite for the word "indefinite".

Good news, then? Not entirely. Quite brilliantly, Mr Obama has constructed the persona of the anti-war campaigner. Many, home and abroad, have come to treat him as though he has just finished burning his draft card. In an America that now regrets Iraq bitterly, and in a Europe that despised the venture from the start, the notion has heartened and inspired millions.

Mr Brown, equally, may face a sea of troubles while the Democrat floats on a rising tide, but his problems are mainly domestic. Even among his enemies the belief persists that, had he been in charge, the story of Britain's involvement in the Iraq war would have been very different. Nothing in the record, such as it is, supports the supposition, but it lingers.

Which brings us to Afghanistan. You could say, if generous, that this is the war that should have been fought first and last, that Iraq always was (for it always was), at best a distraction, at worst a fantasy of strategic power. In the dash for Baghdad and the oilfields - never forget the oilfields - the source of the clear and known terrorist threat was neglected. So the briefly pulverised Taliban reassembled. It counts as an important clause in the indictment against Bush and Blair.

Even that now-commonplace assessment does not quite explain everything, however, that is going on in Afghanistan. The first assault, in the aftermath of the Twin Towers, had a purpose that most could understand and support: to force the Taliban to hand over Osama bin Laden and those others responsible for the carnage in Manhattan. It was, in the old sense, a police action. But that was all it was supposed to be.

In those days, remember, the Bush administration "didn't do nation-building". It had the broad support of the world in the hunt for bin Laden. There was no real moral or legal problem. Instead, the task was neglected shamefully in favour of the lie that named Saddam Hussein as the fount of all international terrorism. Result: millions of Iraqis have since died or fled and Afghanistan has a new Taliban problem.

Hellish, no doubt, for Afghans. You might say that a debt is owed to them, given previous failures. Instead, western governments have said a great many, often contradictory things. Fight to find bin Laden. Fight to eradicate the heroin trade. Fight to secure Pakistan (the wrong end of the telescope is used for that one). Fight to finish off the Taliban, aid reconstruction, prevent the next terrorist outrage. Fight even for certain pipeline routes.

It is all a little fuzzy, in other words. As with Iraq, the proffered explanations tend to alter with circumstances. All we actually know is, first, that little of it has much to do these days with bin Laden, who remains at large; secondly, that invaders tend to have unhappy experiences in Afghanistan. Wars last a long time, and rarely achieve much.

So we can count on Mr Obama, then, and on Mr Brown, to avoid that sort of mess? Right. In fact, the former believes that Afghanistan now is vastly more important as a battlefield than Iraq ever was. He intends, he says, to increase greatly the American military presence in that theatre.

Britain is already more deeply involved in Afghanistan than in Iraq. It is costing dear, in blood and money. But Mr Brown does not talk of drawing down troops. Instead, it seems this is long-haul stuff, a commitment, according to some in Whitehall, that could engage forces for decades to come.

Mr Bush and Mr Blair must wonder, sometimes, why they get the rap as the only two certified warmongers in the world. Look beyond Mr Obama's moral purpose and Mr Brown's conception of his duty. What you see is the prospect of the war on terror, never ideologically credible, becoming generational. The best we are being offered is a change of scene.

I can only repeat myself: Mr Obama will not, if elected, be quite the American President of European liberal dreams. Americans may, meanwhile, discover that, as with Mr Brown in these parts, disillusionment can come swift and very hard.