S Arabia's new king and Iran

Saudi Arabia's new king, Salman Bin Abdulaziz Al Saud, has promised continuity, and there's no reason to doubt him -- he has been running the country during his half-brother Abdullah's sickness preceding his death. When it comes to Iran, however, King Salman needs to make a clean break.

The Sunni kingdom's longstanding rivalry with Iran's Shiite regime undermines the very stability Salman claims to want to protect. What's more, rapprochement isn't as far-fetched as it sounds.

The Middle East is changing much faster than the House of Saud. Just hours before Abdullah died last night at age 90, the president and government of Yemen, Saudi Arabia's southern neighbor, resigned and left the country to Houthi militiamen reportedly financed and armed by Iran. Little could be more disturbing for the new Saudi leader, who until today had been the country's defense minister.

The Houthi takeover puts two visceral Saudi Arabian enemies -- al-Qaeda and (by proxy) Iran -- in Yemen to the south, and two more -- Islamic State and (again by proxy) Iran -- in Iraq to the north. From the capital Riyadh, the Houthis will be viewed much as Hezbollah is seen from Tel Aviv: as foot soldiers willing to do mischief at the bidding of the Revolutionary Guard in Tehran.

Yet trying to fight Sunni al-Qaeda and the Shiite Houthis simultaneously would present King Salman with the kind of Gordian knot of interests that tied up King Abdullah, not to mention the U.S., in Syria. There, Saudi Arabia's decision to arm and finance opponents of President Bashar al-Assad -- an ally of Iran -- has ended by empowering Islamic State and al-Qaeda, both of which would like to destroy the House of Saud.

It's by now clear that Saudi Arabia faces a stark choice: pursue an ever-expanding sectarian proxy war with Iran that strengthens both Sunni terrorist groups, or seek rapprochement with Iran.

Saudi-Iranian enmity is not as unrelenting as commonly believed. It has waxed and waned since the 1979 revolution in Tehran, reaching detente during the rule of Iran's former President Mohammad Khatami, a reformist. Saudi Arabia even reached out to start talking again with President Mahmoud Ahmadinejad, when he was in power, although the effort came to nothing.

But sometimes some discontinuity is called for, and that's the case with Saudi-Iranian relations. The alternative is continued chaos in Syria and Iraq, a new failed state in Yemen and a much freer hand for al-Qaeda in the Arabian Peninsula. In that case, change may soon seek out King Salman.