Warfare, severe food shortages and disease are devastating Yemen, already one of the world's poorest countries. The U.N. has called the situation the "largest humanitarian crisis in the world," and U.N. Ambassador Nikki Haley said recently that "no one should ever have to live the way the people of Yemen are living."

Why it matters: The U.N. estimates that more than 22 million Yemenis are in need of humanitarian assistance. The population of Yemen is 27 million.

By the numbers

• There are 17.8 million food-insecure people in Yemen, according to the U.N. Office for the Coordination of Humanitarian Affairs (OCHA).
• Around 7 million people are on the brink of famine.
• 13% of total Yemeni casualties are children; There have been more than 8,700 conflict-related deaths and more than 50,000 injuries.
• "An average of 65 people have been killed or injured every day since the escalation of the conflict," according to OCHA's Humanitarian Needs Overview (HNO).
• 16 million Yemenis don't have access to "safe water and sanitation," per the HNO.
• There are an estimated 1 million cases of cholera.
• There are 2 million internally displaced people.

How we got here

• Yemen is nearing its third year of war between two factions: Houthi rebel forces and a Saudi-led coalition which supports President Abdrabbuh Mansour Hadi.
• Former president Ali Abdullah Saleh, who was killed last year, relinquished his office to Hadi in 2011. Houthi rebels eventually "took advantage of the new president's weakness," after Hadi struggled with several problems in office.
• Hadi fled the country in 2015, leading the Saudis and other Sunni Arab nations to begin "an air campaign aimed at restoring Mr. Hadi's government."