Yemen-based al-Qaeda in the Arabian Peninsula (AQAP) attacked a Saudi border post along the Yemeni border on July 4, killing a Saudi border guard and a Yemeni soldier. Concurrently, Shiite Houthi rebels in Yemen seized control of the city of Amran. The events have once again prompted Saudi Arabia to put Yemen at the top of its national security concerns.

Some observers see similarities between developments in Yemen and what is happening to the north of Saudi Arabia with the escalating Sunni-Shiite sectarian conflict in Iraq and Syria and the advancement of the Islamic State (IS). IS has managed to gain strength and territory through an alliance with tribal forces that provide it with a popular base and means of support in both Iraq and Syria.

The progress of the Islamic State and its allies in Iraq and approach to Baghdad, which represents an Iranian red line, has been mirrored in the southern Arabian Peninsula by the advancement of the Houthi forces to the point of their approaching the gates of Sanaa. With the Middle East a chessboard in a match between Tehran and Riyadh, some Saudis are drawing parallels between current events, theorizing that if Baghdad or part of it falls into the hands of Sunni groups, Sanaa might well fall to Shiite groups.

The Houthi advancement in Yemen is purely Yemeni, but this does not lessen the signicance of the ties between the Houthi movement and Iran. In 2013, US Sen. John McCain declared the Houthis in Yemen more dangerous than al-Qaeda, given the relationship between the Houthis and Iran and Tehran's agenda in the region.