Gideon Rachman writes for the Financial Times:
"Historians are sometimes divided into lumpers and splitters. The splitters like to chop problems up into lots of small bits. The lumpers like to link them altogether.
"Would-be Middle East peacemakers can be categorised in the same way. The lumpers want a "comprehensive peace settlement" that links together all the problems in the region - Iraq, Lebanon, Syria, Israel-Palestine, even Iran. The splitters want to deal with all these problems separately."
"The attractions of lumping are obvious. The idea of fixing the whole of the Middle East in one go is delightful. And it is true that all of these problems are linked. To take just one example, Iran's poisonous relationship with the US has encouraged it to make trouble in Lebanon and Palestine, by sponsoring Hizbollah and Hamas.
"But while lumping works as an argument, it risks failing as a policy. There are three obvious problems. First, there is the risk of being over-ambitious. If nothing is resolved until everything is resolved there is a risk that you will end up with nothing.
"Second, there is the problem of which end of the lump you attack first. The much-reviled neoconservatives were also lumpers. But they thought that change in Iraq was the key to the transformation of the Middle East. Mr Miliband, in common with most mainstream European politicians, sees an Israeli-Palestinian peace settlement as the key to the lump.
"This brings us to the third problem with the lump thesis. It is not clear that progress in one area will necessarily unlock the others. Let us say that the Iranians are miraculously persuaded to abandon their nuclear ambitions. Does that automatically lead to the establishment of a viable Palestinian state? Clearly not. Or put it the other way round: let us say the Israelis are miraculously persuaded to grant the Palestinians a viable state. Does that persuade the Iranians to abandon all thoughts of pursuing nuclear weapons? Clearly not. In fact, linking Iran and Israel-Palestine could inadvertently do the Iranians a favour, by tacitly conceding them a legitimate role in Gaza and in Lebanon.
"What probably is true is the more modest claim: significant progress in one area would improve prospects in another. So if there were a rapprochement between Iran and the US that involved the Iranians cutting off support for Hamas, the Israelis would feel more secure - and that might make a Middle East peace settlement easier to achieve. Similarly, the establishment of a proper Palestinian state would remove a source of anger and anti-western grievance across the region, and so undermine an angry, anti-western regime such as Iran."
"I think, as a matter of practical politics, Mr Obama will have to be a splitter. The state of the American economy is going to eat up most of his working day. When he turns to foreign policy, the Israeli-Palestinian problem will come fairly low down his list of priorities - behind, in rough order of urgency, Iraq, Afghanistan, climate change, Iran, international economics and Russia."