There have been reports of air strikes hours after the Saudi-led coalition announced an end to its four-week air campaign against Houthi fighters.
The deputy governor of Aden, Nayef al-Bakri, told Al Jazeera that an air raid targeted tanks used by the Houthis and their allied forces in the southern port city.
Houthis also reported air strikes in the central city of Taiz, Houthi fighters captured the compound of an army brigade loyal to the government in Yemen's central city of Taiz following heavy fighting.
A Saudi air strike was conducted on the brigade headquarters shortly afterwards, residents said.
The brigade, along with several other formations, had declared its loyalty to exiled president Abd-Rabbu Mansour Hadi, opening up a new front in the conflict against the Houthis, according to Reuters.
Renewal of Hope
The coalition had announced that its 27-day military operation "Decisive Storm" had ended by midnight on Tuesday (21 April) and that a new campaign aimed at protecting civilians and preventing Houthi fighters from operating had begun.
The Saudi-led coalition's spokesperson, Brigadier-General Ahmed al-Asiri, said the coalition had achieved its military goals in Yemen and a new operation, called "Renewal of Hope", would aim to protect civilians and combat "terrorism".
"The primary goals of the campaign have been achieved... Houthis are no longer a threat to Yemenis or neighbouring countries. The Yemeni government will now undertake all necessary actions to start rebuilding the country," al-Asiri said in a press conference in Riyadh on Tuesday at midnight local time (9pm BST).
Al-Asiri said political, diplomatic and military action would be combined, but the main focus would be on the political process.
However, the spokesman revealed that "operation restoration of hope" is subject to a number of conditions, and he did not rule out future air strikes against the pro-Iranian Houthi rebels.
He added the coalition would continue to impose a naval blockade on Yemen.