Witnesses say that al-Qaida fighters have been seen in southern Yemeni cities, nearly a month after the militants withdrew from the towns following tribal-led negotiations.

Local residents reported Thursday that al-Qaida militants were seen in the cities of Jaar and Zinjibar, the provincial capital of Abyan province. They say that during the day fighters can be seen driving pickup trucks mounted with anti-aircraft guns, but at night they retreat to hideouts.

The residents spoke on condition of anonymity for fear of reprisal.

Al-Qaida and Islamic State group militants have exploited the security and power vacuum after rebels known as the Houthis seized the Yemeni capital in 2014 and the president fled to Saudi Arabia. The militants withdrew this spring under pressure from a Saudi-led coalition that is fighting the Houthis.