Yemen has been torn apart by conflict since 2014, when Houthi rebels, allied with troops loyal to former President Ali Abdullah Saleh, captured much of the country, including the capital, Sanaa.
A coalition assembled by Saudi Arabia launched an air campaign against the rebels in March 2015 to try to restore the internationally recognised government of President Abd Rabbu Mansour Hadi to power.
Since then, the conflict has killed more than 10,000 people, forced millions from their homes and pushed the improverished country to the brink of famine, according to the United Nations.
The Arab coalition's campaign of air raids has devastated Houthi positions, ammunition depots and bases, but has largely failed to pave the way for the recapture of Sanaa.
Source: Al Jazeera