Pro-government forces in Yemen, backed by Saudi Arabia, have begun attacking a key port held by rebel fighters, BBC reports.
The coastal city of Hudaydah is where most of the aid arrives for people in Yemen's rebel-held areas. Agencies have warned of a humanitarian catastrophe.
About eight million people are at risk of starvation in the war-torn country.
Pro-government strikes began after Iranian-backed Houthi rebels ignored a deadline to withdraw by midnight (21:00 GMT on Tuesday).
It is the first time the Saudi-led coalition of mostly Gulf states has tried to capture such a well-defended major city in Yemen.