It’s been a crisis in the making and simmering for years, escalating in months into armed conflict, and leading to regional intervention in a matter of days.
Yemen's president had barely appealed for military assistance to halt the advance of Houthi fighters when Saudi Arabia responded by launching air strikes against the group.
The Houthis have long been pressing for greater autonomy and political rights but were widely condemned when they staged a coup in January.
Commenting on the military intervention, Saudi Arabia’s ambassador to the US, Adel al-Jubeir, said: "We will do whatever it takes in order to protect the legitimate government of Yemen from falling and from facing any dangers from an outside militia."
Saudi Arabia is co-ordinating a coalition of 10 nations, including Gulf states Qatar, the United Arab Emirates, Bahrain and Kuwait, along with allies Egypt, Jordan, Morocco, Pakistan and Sudan.
The US is providing intelligence and logistical support.
Iran, which has been backing the Houthi rebels, called the air strikes an "invasion" and a "dangerous step" that will worsen the crisis.
Could this military intervention pave the way for a ground offensive?
Or can the UN seize the opportunity to encourage Yemen’s warring sides back to the negotiating table?
Presenter: Folly Bah Thibault
Hussain Al Bukhaiti - Representative of the Houthis and the brother of the group's official spokesman.
Abdullah Baabood - Director of the Gulf Study Centre at Qatar University.
Mohammad Marandi - Iranian Academic and professor at the University of Tehran.
Lawrence Korb - Senior Fellow at the Center for American Progress, and a former Assistant Secretary of Defense.
Source: Al Jazeera