The Shia insurgency in Yemen, also known as the Houthi rebellion, Sa'dah War or Sa'dah conflict is a civil war in Northern Yemen. It began in June 2004 when dissident cleric Hussein Badreddin al-Houthi, head of the Shia Zaidiyyah sect, launched an uprising against the Yemeni government. Most of the fighting has taken place in Sa'dah Governorate in northwestern Yemen although some of the fighting spread to neighbouring governorates Hajjah, 'Amran, al-Jawf and the Saudi province of Jizan.

The Yemeni government alleged that the Houthis were seeking to overthrow it and to implement Shī‘a religious law. The rebels counter that they are "defending their community against discrimination" and government aggression. The Yemeni government has accused Iran of directing and financing the insurgency.

In August 2009, the Yemeni army launched a fresh offensive against Shia rebels in the northern Sa'ada province. Hundreds of thousands of people were displaced by the fighting. The conflict took on an international dimension on 4 November 2009 as clashes broke out between the northern rebels and Saudi security forces along the two countries' common border and Saudis launched an anti-Houthi offensive. The rebels accuse Saudi Arabia of supporting the Yemeni government in attacks against them. The Saudi government denied this. Houthi leaders claim that U.S. involvement in war started on 14 December when the U.S. launched 28 air raids.

Sa`dah (Arabic: صعدة‎ ‏‎‎Ṣa'da) is the capital city of Saada Governorate in north-western Yemen. It is located at 16°56′9″N 43°45′52″E / 16.93583°N 43.76444°E / 16.93583; 43.76444Coordinates: 16°56′9″N 43°45′52″E / 16.93583°N 43.76444°E / 16.93583; 43.76444, at an elevation of about 1,800 meters. Its population in 2004 was estimated at 51,870. It was formerly identified with Karna, the kingdom of the ancient kingdom of Ma'in, which is now known to be identical to the ancient Qarnawu near the modern Ma'in in Al Jawf Governorate.