Middle East: Obama's problem that will not go away
At the threshold of the New Year, a president who sought to re-balance or pivot US foreign policy towards the Asia-Pacific, finds US diplomacy firmly mired in the overlapping conflicts of the Middle East.
Indeed this "Rubik's Cube" of inter-locking catastrophe and crisis looks set to occupy the Obama administration for much of its final years in office.
For a start there is the ongoing struggle against the Islamic State (IS) movement that straddles a swathe of territory in both Syria and Iraq.
Then there are the "civil wars" in those two countries. One, in Syria declared and joined, as various groups, (including IS) seek to over-throw the regime of President Assad.
The other, as yet undeclared, in Iraq but forever bubbling beneath the surface, as Sunni Arabs and Kurds uneasily co-exist with a Shia-dominated central government in Baghdad, within the institutional frame-work bequeathed by the Americans after the removal of Saddam Hussein.
That government - just like the Assad regime in Syria - is strongly backed by Iran.
Indeed Tehran has provided military equipment, troops and high-level military advice to help the crumbling Iraqi military stand-up to the IS onslaught.
In the last few days an IS sniper reportedly killed an Iranian general from Iran's Quds Force - the expeditionary special forces wing of the Iranian Revolutionary Guards - during the fighting in the city of Samarra in central Iraq.
So in a curious juxtaposition, Iran and the US find themselves as de facto allies against IS, though the extent to which this objective relationship may lead to genuine detente is open to question.
Washington and Tehran are still divided by their broader world view; the charge of Iranian support for terrorism; and its antipathy towards Israel.
Then, of course, there is the matter of Iran's nuclear activities where a long-standing diplomatic resolution remains elusive.
The Syrian catastrophe has prompted tensions between Washington and a number of its long-standing allies in the region as countries like Saudi Arabia, many of the smaller Gulf States and Turkey all seek to back specific groups opposed to the Assad regime.
The arming and financing of such groups - many of them Islamist in nature - has inevitably prompted unease in Washington, always sensitive to the boundaries between insurgency and groups that might be linked in one way or another to al-Qaeda.
Turkey's ties with Washington have also been strained since Ankara - with its own regional ambitions - has prioritised the removal of President Assad over the campaign against IS.
Turkey's attitude to the potential fragmentation of Iraq is also complex given its long-standing difficulties with its own Kurdish minority.
If this agenda wasn't crowded enough you can add in the worsening relationship between Israel and the Palestinians, with the West Bank Palestinian leadership threatening to take the dispute to the UN Security Council in a bid for a resolution that might call for an end to the conflict.
The resurgence of violence between Israel and the Hamas-led entity in the Gaza Strip remains a real possibility.
An Israeli general election in 2015 could potentially make the domestic political atmosphere only more febrile though a change of Israeli government could open up fresh diplomatic possibilities.
Relations between President Obama and the Israeli Prime Minster Benjamin Netanyahu have been poor almost from the outset.
Such tensions might be seen as transient, dependent to an extent, upon the personalities involved.
However they come at a time when there is growing international antipathy towards Israeli settlement activity on the West Bank - especially in Europe.
There is also broader generational change at work - even within the US, including within the US Jewish community - which suggests that while support in the US for Israel's security may not be on the wane, it may become more conditional and dependent upon Israel's actions in the future.
Arab Spring fall-out
If all of this wasn't a packed enough agenda with which Washington has to grapple, then the wider Middle East is still suffering from the fall-out from the largely failed hopes of the so-called "Arab Spring".
The chaos in Iraq and Syria - the heartland of the Arab world - has raised fundamental questions about the survival of the borders and much of the state system bequeathed to the region by the colonial Western powers.
So in the face of this raft of problems can Mr Obama begin to make a difference?
Rightly or wrongly the president's whole approach to foreign policy has been widely criticised for indecision and a lack of any real strategic vision.
He has failed, say his critics, to become the master of the Washington machine; the inter-agency process has often sought simply to find the policy that is the lowest common denominator.
Congress is now firmly in the Republicans' hands and at this stage in an administration's life-cycle many of the more able people are leaving or thinking of their careers beyond government.
But that is only part of the story. In recent weeks Mr Obama has shown a new tenacity in foreign affairs and a willingness to use his last two years of office to strike out in new directions abroad.
There was, for example, the historic shift of US policy towards Cuba. And if Hollywood, the home of the action hero, appeared to wilt under North Korean pressure, the president did not.
There was too the renewed extension of the interim agreement with Iran on its nuclear programme.
Opinions differ but Mr Obama neither made concessions that might have yielded a weak deal, nor did he walk away from the table believing that there was still an opportunity to be seized.
Diplomacy with Iran offers one of the great foreign policy challenges for the remainder of Mr Obama's tenure in the White House. But it is not the only one.
Mr Obama has to contend, not least, with the newly assertive policies of the Russian President Vladimir Putin.
This raises all sorts of wider diplomatic questions quite apart from the need to re-vitalise Nato and reassure worried European allies.
Can Mr Obama, for example, continue to count on Russian support to keep the pressure on Tehran? What of Russia's continued backing for the Syrian President?
Then there is the need to push on with that much-vaunted "Asian pivot".
However, given the turmoil in the Middle East it is there that US leadership may be tested the most.
- Tomorrow, Jonathan Marcus focuses on five key issues that Obama must address in the Middle East.