From the viewpoint of the Saudi authorities, such a wide border is seen as the main point of penetration for extremists and terrorists such as al-Qaeda into Saudi Arabia. You only have to look at the list of detainees at Guantanamo Bay to know that Yemen has been a fruitful recruiting ground for al-Qaeda.
A majority of the 800 prisoners listed in recently published detainee assessments were Yemenis. Back in the 1990s, most of Osama bin Laden’s bodyguards were recruited from Yemen. Since 9/11, the Saudis have invested heavily in stamping out the threat at home from al Qaeda, and the last thing they want is contagion seeping in from next door and it made a major investment in Yemen in term of development and advancement. Therefore, military and financial support from the central government of Yemen is not only wise but necessary to its national security and military strategy.
In the West’s view, by controlling Yemen through the Houthis, Iran is aiming to increase its strategic and regional influence and is desirous for acceptance of its positions in Syria and Iraq, which is not desirable to the Arab-Western axis. In their view, the Houthis are the Iranian forces in Yemen, and Iran is a geopolitical threat to the axis.
According to Saudi Arabia, the Pahlavi regime collapse caused the geopolitical void in the region and it paved the way to Saudi Arabia to be a regional power, but the Islamic revolution complicated matters for the Saudis. In the Iraq-Iran war, Saudi Arabia tried to help Iraq. After the war, however, Iran became more powerful in the Middle East. The stabilization of Iran’s position in Iraq, Lebanon, Syria, Bahrain and Yemen led Saudi Arabia to see Iran as a big threat. Confrontation increased.
From Saudi Arabia’s view, the Yemeni Shiites are the last ring of the Shiite crescent, and their victory would mark a complete collapse of its military goals and its regional power, and would also constitute a threat to its territorial integrity.
Perhaps this is why, despite the international criticism and intense media outrage against Saudi Arabia for the humanitarian catastrophes and war crimes in Yemen, the U.S. continues to support Saudi Arabia as its important ally in the Middle East.
Unlike some Arab countries whose oil is paramount, Yemen’s strategic location at the south of the Arabian Peninsula and on the vital sea lanes has ramped up the importance of Yemen both to the Saudis and the West.
The Gulf of Aden in southern Yemen is an important port area at the intersection of one of world’s busiest shipping lanes. During colonial British times, the Aden area was used as a coal station for the British merchant marine.
The daily passage of millions of barrels of oil, the maritime traffic of trade towards the Suez Canal and the Saudi Refinery in Yenbu’, and the flow of oil tankers and other commercial vessels to destinations such as China and Europe, have given special importance to the Gulf of Aden and the Strait of Bab al-Mandab. The presence Somali pirates also greatly enhances the importance of stability and security in Yemen in general and the Gulf of Aden and the Strait of Bab al-Mandab.
The West is concerned that instability and insecurity on the frontier of one of the world’s oil giants may cost them. According to Saudi statistics, a production rate of 11 million barrels of oil per day plays a very important role in the world’s energy market, as most of Saudi oil goes to developed Western countries, as well as emerging countries such as China and other parts of East Asia.
The importance of control over Yemen for Saudi Arabia and the West is obvious. Instability along Saudi’s border with Yemen seems a threat to the global political and economic order as determined by the West and the Saudis.