Not a month goes by without another statement by someone at odds with the participation of the coalition in the conflict in Yemen. In September, a group of US senators attempted to block a deal to sell arms to Saudi Arabia. In October, members of the UK Labour Party called to withdraw UK support from the coalition, while appeals to "end the war" in Yemen have been made in other newspapers and magazines.
The compilation of these views all point to a line of reasoning: withdrawing support leads to the coalition disengaging. Disengagement will create peace. But the fact that this view has taken hold in some circles necessitates asking the question of what disengagement might look like.
The primary point that is difficult to dismiss is that the Arab coalition’s departure from Yemen could create a significant security vacuum. As the conflict evolves into a more static phase, both sides will come closer to the realisation that gains are more likely on the negotiating table than the battlefield. This is contrary to the conflict in Syria where the regime knows that it can still make gains on the battlefield, thus using greater amounts of military force.
Any withdrawal of the Arab coalition is likely to tip the scales in the balance of the pro-Houthi faction. Their opponents, Yemen’s government, will find it difficult to ensure a balance of power with the Houthis, again vital to any peace deal, and deal with the threat from Al Qaeda in the Arabian Peninsula at the same time.
The sequence of events unleashed by any coalition withdrawal would potentially resemble a hybrid of Vietnam in 1975 and Iraq in 2011 to 2014. The pro-Houthi faction would find the prize of South Yemen too enticing to allow a negotiated settlement. A peace agreement between North and South Yemen might as well be written with the same piece of paper as the 1973 Paris Peace Accords between North and South Vietnam.
An offensive strategically similar to the one launched by North Vietnam would be launched by pro-Houthi Yemen. Supported by arms that Iran may or may not be providing, the pro-Houthi faction would drive southward until it has taken Yemeni government-held areas. Under those conditions, the offensive would almost certainly succeed, with two significant effects.
First, the invasion would exacerbate Yemen’s dire humanitarian situation and create a new refugee crisis that the Arab coalition now out of the country, and the international community will be limited in their ability to influence.
It is likely that a repeat of the 1975 to 1995 Vietnamese exodus, in which more than 800,000 "boat people" escaped Vietnam, would take place. Second, whoever in the south did not flee the Houthis will be more likely to be driven into the arms of those who would be able to fight, and in Yemen after a Houthi takeover, that is likely to be Aqap. Here the comparison to Iraq could apply, where an ostracised predominantly Sunni population, or at least its most susceptible elements, are likely to side with a terrorist movement as they become politically disenfranchised and perceives oppression. While ISIL’s pool of recruits in Iraq mostly comes from the 7 million Sunni Arab population, the 12 million Sunni Arabs in Yemen provide an even larger pool of people who could be pushed into terrorist groups.
Critically, Aqap proved that it has developed the ability to take, hold and govern terrain as it showed in 2012 and 2015. It is not far-fetched that next time it controls territory it will attempt to create a political entity, following the example of ISIL. Its transnational history means that it is also not far fetched that this entity would try to branch outside of Yemen.

Source: The National