The Gulf allies are backing two different sides adding another layer of complexity to year-long conflict.
Back in 2015 Saudi Arabia and the United Arab Emirates intervened in Yemen to counter the influence of their common regional foe: Iran. Now the two energy-rich Arab monarchies are on opposite sides as their local partners fight each other.
The conflicting interests of various groups fighting in the Middle East’s poorest country came into focus this month after Yemen’s internationally-backed government openly accused the UAE of supporting separatists in the south.
Thousands of people, including children, have died as a direct result of fighting or starvation in a conflict where regional powers including Iran face accusations of ignoring civilian casualties.
The latest bout of tensions, which has seen the Southern Transitional Council (STC) forces run over parts of the port city of Aden, was triggered by the killing of senior STC commander Munir Mahmoud, commonly known as Abu al Yamama.
The STC seeks secession from Yemen to form a separate state which existed between 1967 and 1990 under the influence of the former Soviet Union.
Yamama, 44, was a key member of STC’s ground forces - the Security Belt - rising through the ranks to become its commander. He was from a powerful southern tribe and was widely respected for his years-long struggle for the southern cause.
“It’s a serious loss to the STC. He was very active all over the south. While he was based in Aden, he travelled around to other areas,” a senior STC leader told TRT World.
The STC, like the Yemeni government of President Abd Rabbu Mansour Hadi, has fought Houthi rebels, who receive support from Tehran.
While the Houthis claimed responsibility for the August 1 attack on a military parade in which Yamama was killed along with dozens of other STC fighters, the southern leadership blames a Muslim Brotherhood-affiliated party aligned with Hadi.
The Islamic al Islah party is seen as one of the main reasons behind the friction between UAE-backed STC and the Saudi-aligned Hadi government. The UAE is particularly wary of Islamist parties such as the Muslim Brotherhood, which threatened its rule.
The UAE has militarily supported the STC, which controls the Security Belt forces while the Saudis have sheltered and provided arms to Hadi-led government forces.
The complex and conflicting alliances in Yemen have been influenced by recent developments in the region.
Days before Yamama’s death, the UAE said it was pulling out its ground troops and military equipment as part of a drawdown. That was followed by a meeting between senior UAE and Iranian military officials to discuss maritime security.
Experts say the UAE wants to avoid confrontation with Iran, which faces Amercian sanctions and accusations of attacks on oil tankers off the coast of the UAE.
The STC, which relies on the UAE for financial and material support, was initially at pains to acknowledge the new reality as it was quite apparent that the southern forces were on the backfoot.
That however changed as Yamama’s death gave a new push to the STC and triggered massive demonstrations.
In 2015, the Houthis captured many cities and towns in Yemen, including the capital Sanaa, and forced Hadi to flee first to the southern port city of Aden and then to Saudi Arabia.
Since then the Saudi-led coalition has conducted an intense campaign of air strikes against the Houthi targets, which human rights groups say have resulted in thousands of civilian deaths.
On the ground, especially in southern Yemen, the UAE has been more active, funding and controlling different militias including Colombian mercenaries with the ostensibly stated aim of ‘fighting Al Qaeda.’
However, multiple reports over the years have come out that say that the UAE often arms and pays militants for its own purposes.