The success of Yemen’s southern secessionists in taking over the city of Aden has opened a new chapter in the country’s sordid history. It has effectively undermined all efforts to restore legitimate authority to the government of President Abd-Rabbu Mansour Hadi and is endangering the territorial integrity of the country.

After the United Arab Emirates (UAE) decided to withdraw the bulk, if not all, of its soldiers from Yemen, it was inevitable that the secessionists would make a move against Hadi’s forces in the south. In fact, what happened is very much part of the Emirati plan for southern Yemen, and particularly Aden and its seaport.

The UAE’s love-hate relationship with Yemen

Geographically distant from Yemen, the UAE did not have the same degree of trepidation Saudi Arabia felt about threats and developments in that country over the past decade. Whether these emanated from the Houthi rebels on the kingdom’s southwestern border or from al-Qaeda in the Arabian Peninsula to its immediate south, they generally did not affect the security of the UAE.

This was the case before Yemen’s descent into civil war in 2015 following the collapse of the multi-party dialogue under the so-called Gulf Initiative. Several factors precipitated the change in the UAE’s nonchalant attitude toward Yemen, including the Houthis’ move to control central authority, their alliance with former President Ali Abdullah Saleh, and their advance in the south and occupation of Aden and its environs.

Emirati decision-makers could not completely ignore the potential danger that instability in Yemen might present to the collective security of the Arabian Peninsula and the Gulf Cooperation Council (GCC). Furthermore, the Houthis threatened their interests in Yemeni ports (most importantly Aden), which has been part of the UAE’s roadmap to become a major naval and commercial player in the wider region that stretches from the Arabian Gulf to the Mediterranean Sea.

Since the mid-2000s, the UAE has succeeded in striking deals with several states along this stretch to manage commercial ports and establish military bases. The UAE has footprints in Djibouti, Somaliland and Puntland (both federated states in Somalia), and Eritrea.

These considerations have been at the heart of the Emirati strategy in Yemen since the launch of Operation Decisive Storm in March 2015. However, for the Emiratis, stopping the Houthis and maintaining the collective security of the GCC did not necessarily mean the restoration of Hadi’s legitimate authority over the country.

To be sure, the Yemeni president never believed that the UAE was working to restore his legitimate rule and had fallen out with its strongman, Abu Dhabi Crown Prince Mohammed bin Zayed (MBZ) a long time ago.

Indeed, the UAE has had a Janus-faced relationship with Yemen since the start of the Saudi-led coalition’s operations there in March 2015. While officially supporting the Hadi government, in practice, the UAE has been helping and sustaining its opponents in the south and paving the way for secession.

After recapturing Aden from the Houthis, Emirati forces and their Yemeni allies continued to push northward toward Mokha and Hodeida, which both possess strategic maritime facilities, and imposed a siege on Yemen’s western coast to limit the Houthis’ ability to import weapons.

The last UAE military action on the ground occurred toward the end of 2018 when it supported Yemeni troops against the Houthis around Hodeida. Following that push, Martin Griffiths, the United Nations Special Envoy for Yemen, negotiated the Stockholm ceasefire agreement around Hodeida that continues to hold today.

The seemingly endless nature of the Yemeni war – now a quagmire in its fifth year – a slowing UAE economy, and tensions in the Gulf necessitated retrenchment and withdrawal from Yemen. Still, gains in the south of the country could not be forfeited, nor could the UAE’s local allies be abandoned. That is why Abu Dhabi decided to allow the secessionist Southern Transitional Council (STC) to execute a coup against the Yemeni president and his government.

It is quite likely that the battle for Aden and its strategic facilities is only the beginning of a series of showdowns elsewhere whose ultimate aim is to remove all vestiges of Hadi’s control in the south.

Whither Saudi Arabia?

Saudi Arabia’s position on what happened in Aden in early August has been rather murky. News reports from the city and statements by Hadi government officials point to Saudi inaction against the secessionists. But no matter its current stance, Riyadh appears incapable of delivering on promises it made to Hadi when it decided to launch Operation Decisive Storm.

Things did not have to be this way. With its extensive relations with Yemeni political factions, Saudi Arabia could have helped the negotiators during the multi-party dialogue meetings after 2012 to arrive at a compromise for a new Yemen in which all factions could have a role. It also could have assisted United Nations envoys Jamal Benomar and Ismail Ould Cheikh Ahmed when they were negotiating for compromises between the Yemeni government and the Houthis.

Instead, Saudi Crown Prince Mohammed bin Salman (MBS) hitched his wagon to MBZ’s horse, apparently with no clue as to where the UAE was taking Saudi Arabia and Yemen. After four and a half years of military action in Yemen, MBS can hardly claim any success, as MBZ runs away with Yemen’s south.

The Houthis are still entrenched in Sanaa and other areas and continue to attack vital installations in Saudi Arabia with missiles and drones. The humanitarian disaster in Yemen­ – caused in almost equal measures by the Saudi-led coalition and the Houthis – is mostly blamed on Saudi operations, earning Riyadh unwanted international opprobrium.

Saudi Arabia’s anti-Iran axis also appears to give way. While Riyadh continues to insist that the US take more aggressive action on Iran, its partner, the UAE, has started trying to de-escalate tensions with the Islamic republic. Abu Dhabi went out of its way to avoid accusing Tehran of responsibility for attacks on oil tankers in the Gulf region over the last two months and in late July dispatched delegations to Tehran to talk maritime security.

As the UAE tries to slip out of a war it encouraged Saudi Arabia to start, the Saudis may now be wondering: with friends like these, who needs enemies?

Potential future scenarios

If not reversed, the takeover of Aden by southern secessionists may well be the final nail in the coffin of Yemen’s unity and territorial integrity. While Saudi Arabia has announced that it will host reconciliation meetings between Hadi and his adversaries, there is no guarantee that they will be successful. Having allowed Abu Dhabi to do what it wanted in Aden, Riyadh will find it difficult to oppose the further territorial expansion of the STC.

Over the next few weeks and months, a number of significant developments spurred by the crisis in Aden could take place.

First, today’s status quo may hold, allowing the STC to maintain its control over Aden and its maritime facilities. This would be a significant but not full victory for the UAE. After a short period of stalled negotiations between the Hadi government and the STC, the latter may try to take over other strategic maritime centres like Mokha and Hodeida, achieving what the Emiratis desire. If this comes to pass, the UAE would secure Yemen’s coastline as an important base in its strategic plan for the region.

Second, the Hadi government may be successful in holding on to areas in the interior, such as Taiz, Dhale, Lahj, and others, which will effectively create two power spheres in the south. This could encourage more warlords to declare their autonomy in areas they control, which will practically lead to the dismemberment of the country instead of a mere partitioning. This possibility should send shudders down the spines of Saudi leaders who will have to contend with many more players in Yemen than they had to before.

Third, the preoccupation of the Hadi government with the challenge the secessionists pose in the south may give the Houthis an opportunity to increase their military pressure on Saudi Arabia. Given that the kingdom has failed to achieve any of the objectives it declared in March 2015, this pressure may force it to sue for peace. This most likely will result in the establishment of a Houthi-led state in northern Yemen and a vassal state supported by the UAE in the south, in effect putting the lie to the last few years of Saudi regional policy and seriously wounding Saudi credibility for the foreseeable future.

Perhaps that is precisely why southern secessionists encountered little Saudi resistance to their coup in Aden. Seeing that the UAE has abandoned a unified Yemen in order to serve its interest in a friendly southern Yemeni state, MBS may have decided to go along, with the hope that the Houthis will be easy neighbours. Only time will tell how this will play out.

The views expressed in this article are the author’s own and do not necessarily reflect Al Jazeera’s editorial stance.