S ix months after Barack Obama first visited Riyadh, the Middle East is again at the fore of US foreign policy, with Yemen, the Palestinian peace process and Iranian nuclear weapons all vying for his attention.

In all three areas Saudi Arabia, as a long-standing ally of the US, could play a critical role in helping Washington achieve its aims.

For the Palestinian issue, the peace plan unveiled by King Abdullah bin Abdulaziz al-Saud in 2002 remains at the heart of discussions from the Arab point of view.

Obama’s special envoy to the Middle East, George Mitchell, returned to the region in mid January in an effort to restart peace talks between Israel and the Palestinians, but any deviation from the 2002 plan will need the endorsement of Riyadh to gain widespread acceptance on the Arab street.

Riyadh’s role in stabilising Yemen is a further sign of its importance. Riyadh has its own vested interests in its southern neighbour, not least to ensure that the Houthi rebellion in the north of Yemen does not cross the Saudi border. Like Washington, it would prefer to see a strong central government in Sanaa.

Even in the case of Iran – a country with which Riyadh has an uneasy relationship at the best of times – Saudi support for the US position would ensure the issue is not simply one of Tehran against the West.

Six months on, Obama may soon need to make another visit to the Saudi capital.

CAPTION - Allies: King Abdullah welcomes Obama to Riyadh