Claiming that it had "achieved its goals," Saudi Arabia announced on Tuesday that it would halt its air campaign against Yemen. But hours later, the bombing began anew. On Wednesday, Saudi planes struck a military base controlled by Houthi rebels in Taiz, Yemen's third-largest city, resuming a month-long campaign to uproot the Shiite group now in de facto control of the country. The stated goal of the Saudi campaign is to restore Abdu Rabbu Mansour Hadi, Yemen's exiled president, to power.
Yemen has been in crisis since last September, when the Houthis overran the capital city of Sanaa and placed Hadi under house arrest. In the ensuing months, the Houthis' control over Yemen's government, military, and territory has only grown. The group has received help from an unlikely source: Ali Abdullah Saleh, Yemen's former president and Hadi's predecessor, whose government led its own war against the group beginning in 2004. Saleh had relinquished power in exchange for immunity during the Arab Spring in 2012. He has since thrown his support behind the Houthis in an apparent attempt to regain influence in the country.
Complicating this internal dynamic is the rivalry between Saudi Arabia, the region's most important Sunni power, and Shiite Iran. Tehran claims that it has not provided military support to Houthis—but Saudi Arabia doesn't appear to be taking any chances and has implemented a blockade of Aden, Yemen's largest port city, to prevent Iranian ships from delivering weapons.