Yemen's national airline has canceled all flights to the country's only two functioning airports after the Saudi-led coalition battling Houthi rebels announced the closure of all land, air and sea ports.

The tightening of an embargo that has been in place since 2015 came after a ballistic missile fired by the Houthis at an international airport on the outskirts of the Saudi capital was intercepted by air defenses.

Yemenia airlines said Monday that the coalition, which controls Yemen's airspace, had declined permission to fly out of Aden and Sayoun, in southern Yemen.

The two airports are in areas controlled by coalition allies. Yemen's main international airport, in the rebel-held capital, Sanaa, has been closed since August 2016 by order of the coalition.