I wrote about this August 2018, in Reuters: Yemen’s separatists attack military academy in Aden:
- Primary. Houthi versus non-Houthi.
- Secondary. north versus south.
- Tertiary, potential. Zaydi Shia versus Sunni in the north.
The tertiary conflict has yet to occur, impeded by the historical political passivity of Yemen’s Sunnis. The politics of Yemen has been dominated by Zaydi Shia up to the modern period. Ali Abdullah Saleh, the assassinated ruler of Yemen, was himself Zaydi Shia.
Abdrabbuh Mansur Hadi is the first Sunni ruler of modern Yemen. He is a southerner. But should the situation evolve in favor of the Saudi coalition, Hadi may repress the south.
If the Saudi coalition wins, the northern Sunnis will become politicized, simply by association with the winning side. The tertiary conflict could then ignite. With Hadi bogged down in the South, the Houthis could re-ignite the conflict. Resurgence seems to be a general tendency in that part of the world.
If this seems improbable, consider the general liquidity of allegiances. Saleh was the principle opponent of the Houthis before his resignation, even though most Houthis are Zaydi, as was Saleh. He oppressed followers of his own religion.
Until the advent of the Houthis, loyalty was a purchasable commodity.