An Apache helicopter from a Saudi-led military coalition wounded three Yemeni soldiers when it fired a missile at a military vehicle outside Aden International Airport.
The attack struck troops loyal to the airport's chief of security, who had refused to accept a government order that he be replaced.
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 had intervened militarily in power struggles within the Yemeni armed forces.
The Saudi-led coalition has launched thousands of air strikes against the government's foes, the Iran-allied Houthis, in a campaign to restore President Abd-Rabbu Mansour Hadi to power.
It helped wrest Aden from the Houthis, who control the capital, Sanaa, in the summer of 2015.
