Yemen's internationally recognized government has declared a nighttime curfew, starting Monday, in the key southern port city of Aden in a bid to push back against recent incursions by al-Qaida and other Islamic militant groups, the city's governor said.

According to the Aden governor, Aidarous al-Zubaidi, the curfew will be in place every night from 8 p.m. to 5 a.m. for an unspecified period.

The measure came after government forces retook Aden's strategic port after heavy clashes with militants who had seized it earlier over the weekend. Al-Qaida and other militants have been using the port for lucrative smuggling operations.

However, it remained unclear how well the curfew can be enforced since the Yemeni forces, backed by a Saudi-led coalition of mostly Arab states that is supported by the United States, are stretched thin as they battle the Shiite rebels known as Houthis.

Yemen's al-Qaida branch has long been seen by Washington as the most potent affiliate of the extremist network and has been linked to a number of attempted attacks on the U.S. The group, known as the Al-Qaida in the Arabian Peninsula, has captured much of Yemen's sprawling Hadramawt province and its capital, Mukalla, as well as the capital of southern Abyan province, Zinjibar and the town of Jaar.

The group and Islamic State-linked militants have exploited the chaos of the country's civil war to stage significant land grabs and expand its footprint in southern Yemen.

According to U.N. figures, the war in Yemen has killed at least 5,884 people since March, when fighting escalated after the Saudi-led coalition began launching airstrikes targeting the rebels

The conflict pits the internationally recognized government, backed by a Saudi-led coalition against the Houthi rebels, allied with a former president.

The two sides launched peace negotiations in December in Switzerland, and a truce was declared on the ground, which never really took hold as both the government forces and the rebels ignored it. That truce formally ended over the weekend.

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