United Arab Emirates-backed separatists tighten grip of southern Yemen, and airspace briefly closed

ADEN, Yemen — The airspace of war-torn Yemen was briefly closed Monday, an official said, as tensions escalated in the country's south after a separatist group, backed by the United Arab Emirates, took over an oil-rich region in a rift that could fracture the anti-Houthi alliance.

A Yemeni government official said that the Saudi-led coalition didn't issue required permissions for flights to or from Yemen, briefly halting flights to and from the southern city of Aden — the seat of the internationally recognized government.

The official described the move as a ''Saudi message'' to the separatist Southern Transitional Council's latest clashes across southern Yemen, including its seizure of much of the sprawling oil-rich province of Hadhramaut, which borders Saudi Arabia.

The move was later reversed, allowing flight operations in Aden airport, where hundreds of passengers were stranded for hours, said the official, who spoke on condition of anonymity because he wasn't authorized to brief the media.

An Associated Press journalist at the airport said that workers have begun processing passengers of a Cairo-bound flight that was supposed to take off early Monday.

Since the entry of a Saudi-led coalition into Yemen's war in 2015, the coalition has controlled the country's airspace. Saudi Arabia didn't acknowledge closing Yemen's airspace on Monday.

UAE-backed council expands control

Forces of the secessionist group were deployed across the strategic Wadi Hadramout area, which includes major urban centers and military bases, according to STC-allied media. They took over the presidential palace and the international airport in Seiyun last week, and advanced to the province of Mahra, which borders Oman, the group said.

STC hoisted the flag of South Yemen over government buildings across the country's south including on the border crossing with Oman. Images circulated on STC-allied media showed the South Yemen flag, with its light blue chevron and a red star, flying over government buildings and schools in the south.

The separatists enjoy loyalty through much of southern Yemen and have repeatedly pushed to break up Yemen into two countries, as it was between 1967 and 1990.

Hundreds of STC supporters took to the streets in Aden to call for the establishment of an independent state in the south. The demonstrators raised the flag of South Yemen, and pictures of Aidarous al-Zubaidi, the STC leader, who is also vice president of the country. There were also protests in Hadramout.

''It's the summit day, the day of great triumph … when we liberated all regions of the south,'' said Mohamed al-Zaher, a Yemeni resident while flying the flag of South Yemen, which was known as the People's Democratic Republic of Yemen.

STC forces seized the presidential palace in Aden over the weekend, forcing presidential guards to vacate the facility, according to the government official.

The STC sought to portray its military advances as necessary to restore stability in the region, and to fight the Iran-backed Houthis, al-Qaida and the Islamic State group. It said that Hadhramaut Valley has turned into a ''platform for smuggling operations'' for the Houthis and ''hotbeds'' for al-Qaida and IS militants, and that its operations there came after ''the exhaustion of all options proposed in recent years to restore stability.''

The chairman of the ruling Presidential Council, Rashad al-Alimi, meanwhile, on Sunday called for the Emirati-backed forces to withdraw from areas they recently seized in Hadhramaut and Mahra.

''We categorically reject any unilateral measures that would undermine the legal status of the state, harm the public interest, or create a parallel reality,'' he said in a statement following his meeting with diplomats from the United States, United Kingdom and France, in Saudi Arabia's capital, Riyadh.

‘Major shift'

''This changes the balance of power in Yemen,'' he said. ''The key question now is how Saudi Arabia will respond, given the direct implications for its national security.''

The UAE's support for the secessionists has threatened the Saudi-led coalition fighting against the Houthis for more than a decade. The UAE is part of the coalition.

Yemen's war began in 2014, when the Houthis swept down from their northern stronghold and seized the capital, Sanaa, along with much of the country's north. In response, the Saudi-led coalition intervened in 2015 to try to restore the internationally-recognized government to power.

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