Yemen's exiled President Abdrabbuh Mansour Hadi has returned to the southern city of Aden to supervise a new offensive against the rebel-held area of Taiz, officials say.
It is not clear how long Mr Hadi intends to remain in the country.
He made his first visit to Aden in September, having fled the country six months earlier in the face of advances by Houthi rebels.
At least 5,600 people have been killed in the past eight months of fighting.
A Saudi-led Arab coalition launched an air campaign in March, followed by a ground offensive, to push back the Houthis and reinstate Mr Hadi's government.

Officials say the president will be staying at the Maashiq presidential palace in the central Crater district of Aden.
His arrival comes as forces loyal to him are reported to have made advances in the south-west, surrounding the city of Taiz.
About 45 fighters from both sides were killed on Monday, medical sources quoted by the Reuters news agency said.
Residents said coalition warplanes bombed Houthi targets in the city several times on Tuesday.
The president's last attempt to return to his country was in September after six months of exile in Saudi Arabia. He was forced to return to Riyadh after Aden came under rebel attack.
He first fled Aden in late March as Shia Houthi rebels advanced on the city.
UN-brokered peace talks on the Yemen crisis are planned for later this month.

BBC