Personnel from EU maritime mission Eunavfor Aspides’ transport a casualty during rescue operation following an attack by Yemen’s Houthis on the Dutch-flagged general cargo ship Minervagracht, which caught fire in the Gulf of Aden, in this screengrab taken from handout video released on Sept. 30, 2025. Photo: Eunavfor Aspides via X/Handout via REUTERS

Last week, the Saudi Royal Air Force didn’t bomb Houthi rebels or Iranian weapons depots. Instead, in a stunning act of “Blue on Blue” warfare, they bombed the proxy forces of their closest ally, the United Arab Emirates, in the port city of Mukalla.

This was not a mistake. It was a message. And for those in Israel and the US dreaming of a unified “Arab NATO” to counter Tehran, the message is catastrophic: the anti-Iran coalition is officially dead.

The strikes on Mukalla were the kinetic finale to a diplomatic standoff that has been festering for months. In late December, Saudi intelligence flagged a maritime vessel departing from the Emirati port of Fujairah, bound for Mukalla. Its cargo? Not humanitarian aid, but a massive shipment of armored vehicles and heavy weaponry destined for the Southern Transitional Council (STC) — the UAE-backed secessionist movement that has effectively carved a statelet out of South Yemen.

Riyadh’s response was swift and brutal. Viewing the armament of a separatist entity on its southern border as an existential threat, the Kingdom issued an ultimatum that shattered the polite fiction of Gulf unity: withdraw the shipment and vacate the contested positions “within 24 hours,” or face the consequences.

The UAE, perhaps banking on the alliance’s history, called the bluff. They lost.

Saudi jets pounded the 37th Division Camp and the port facilities in Mukalla, destroying the shipment and killing at least seven STC fighters.The psychological impact was immediate. The UAE announced the “conclusion” of its military presence in the area — a diplomatic euphemism for a forced retreat — while their local proxies began a chaotic withdrawal. Witnesses in Mukalla reported a disorganized rout, with retreating fighters looting government buildings and loading refrigerators and washing machines onto military vehicles as they fled toward Aden.

Into this vacuum stepped the “National Shield Forces” (Daraa Al-Watan). Funded, trained, and salaried directly by Riyadh, this new proxy army has successfully retaken Mukalla and the strategic Ash Shihr oil terminal.

This shift represents a fundamental change in the war’s geology. Saudi Arabia is no longer fighting just the Houthis; it is now actively dismantling the infrastructure of Emirati influence in Yemen. The fight is over the “Triangle of Power” — the oil and gas fields of Marib, Shabwa, and Hadramout. Riyadh envisions a pipeline from the Empty Quarter to the Arabian Sea to bypass the Iranian-threatened Strait of Hormuz. An independent, UAE-controlled South Yemen sitting on that pipeline route is a strategic non-starter for the House of Saud.

The implications for Israel and the West are grim. The concept of a monolithic Sunni bloc standing against the Islamic Republic of Iran has been revealed as a mirage. While Saudi F-15s were busy targeting Emirati-supplied armored personnel carriers, the Houthi rebels — Iran’s premier proxy — sat back and watched their enemies destroy each other.

The chaos has already forced the STC to redeploy six brigades of the elite “Giants Forces” (Al-Amaliqa) away from the frontlines with the Houthis to defend their southern strongholds against the Saudis. This leaves the strategic city of Marib vulnerable. If the Houthis seize this moment to launch a new offensive, they could capture Yemen’s last government-held oil fields without facing significant resistance.

Perhaps most alarming is the silence from the West. The Trump administration, despite its “maximum pressure” rhetoric against Iran, appears paralyzed by this internecine conflict between its two key Arab partners. A State Department spokesman issued only a tepid call for “restraint,” highlighting a total loss of American leverage over the Gulf monarchies. The “Big Brother” dynamic, where Washington could pick up the phone and force Riyadh and Abu Dhabi to play nice, is over. The US now faces the nightmare scenario of mediating a war between its own allies while trying to contain Iran.  

The airstrikes in Mukalla are a turning point. The “Blue on Blue” incident proves that national interests in Riyadh and Abu Dhabi have superseded collective security. For Israel, this means that the security architecture of the Red Sea cannot be outsourced to a Gulf coalition that is busy aiming its weapons at itself.

As the smoke clears over Mukalla, the winner is not Saudi Arabia, and certainly not the people of Yemen. The winner is the regime in Tehran, which just watched the American-backed security order in the Arabian Peninsula bomb itself into oblivion.

Amine Ayoub, a fellow at the Middle East Forum, is a policy analyst and writer based in Morocco. Follow him on X: @amineayoubx