Southern Popular Resistance fighters advance along a street during fighting with Houthi fighters in Yemen’s southern port city of Aden.

Coalition airstrikes resumed against Houthi militia positions in Yemen’s main southern city Aden after a five-day ceasefire expired late Sunday, army officials said.

Air raids hit the Houthi-held presidential palace in Aden as well as a base of the pro-Houthi Special Forces in Yemen’s second city, military officials and witnesses said.

Since late March the coalition had been bombing Iran-backed Houthi milita in Yemen, who had seized Sanaa and have swept across many other regions, to stop their advance.

The truce was a Saudi Arabian initiative. It largely held, although clashes between rebels and pro-government forces killed dozens across south Yemen on Saturday.

Ismail Ould Sheikh Ahmed, the U.N. envoy to Yemen, on Sunday called “all parties” to recommit to the truce for at least five more days.

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