SANAA - Members of Yemen's air force shut down the capital's airport on Saturday, stopping all flights in protest at the sacking of their commander, a half brother of former President Ali Abdullah Saleh, an aviation official said. Military vehicles full of soldiers turned passengers away from Sanaa airport and prevented flights from taking off or landing, witnesses said. The action is a challenge to President Abd-Rabbu Mansour Hadi who replaced Saleh earlier this year. On Friday Hadi sacked the air force head in a reshuffle intended to prise key military posts from Saleh's allies and restructure the armed forces, which split during the uprising against Saleh's rule, with some units openly siding with protesters. Protests demanding the resignation of the air force commander, General Saleh al-Ahmar, earlier this year brought several airports to a standstill. Hadi on Friday shifted him to be assistant to the defence minister. The airport's closure highlights the challenges Hadi faces in restructuring Yemen's army, upsetting the entrenched interests of Saleh's associates as well as those of a powerful general, Ali Mohsen al-Ahmar, some of whose allies were also sacked in Friday's shake-up. General Ali Mohsen turned against Saleh early last year along with a chunk of the armed forces, sparking sporadic open combat on the streets of Sanaa with loyalist troops and tribal miltiamen that threatened to push the country into civil war. A committee tasked with demilitarising Sanaa was on Saturday dismantling checkpoints set up by the warring factions in the western part of the city, to enforce a withdrawal of armed tribesmen and troops from the streets by the end of the week.