Amid escalating tensions within Yemen's "liberated" zone, two rival militias tussled for control of Aden airport at the weekend.
Forces commanded by Saleh al-Amiri Abu Qahtan and reputedly paid by the Emiratis have been protecting Aden airport since 2015. On Friday they brought flights to a halt, and according to one account, this was in protest at non-payment of salaries.
Anxious to keep the airport functioning, Aden's governor, Aidarous al-Zubaidi (who has survived at least two assassination attempts since he was appointed in December 2015 following the assassination of the previous governor) asked the Presidential Guard to reopen it. Amiri's forces refused to hand over control to the Presidential Guard, and a stand-off ensued.
The Presidential Guard is controlled by Brigadier-General Nasser Hadi, a son of Abd Rabbu Mansour Hadi who the Saudi-led coalition regards as Yemen's legitimate president (he was "elected" unconstitutionally in a contest where he was the only candidate).
The situation around the airport is still confused. There have been reports of small-scale clashes in the area and on Sunday an Apache helicopter (reportedly Emirati) attacked a military vehicle near the airport. According to the Associated Press, three people were killed in the attack, though Reuters says they were only injured.
Reuters also says the vehicle attacked by the helicopter belonged to Amiri's forces but the Arabs Today website, along with several Twitter users, says it belonged to the Presidential Guard.
Either way, this attack by the coalition on the unruly Yemeni forces that it is defending marks a significant new development. Reuters comments:
"The incident was yet another sign of the inability of Yemen's internationally recognised government to enforce order. But it was the first time its allies, the coalition of mostly Gulf Arab states, had intervened militarily in power struggles within the Yemeni armed forces."