Yemen's Houthi rebels, who launched a wave of attacks on Saudi oil facilities on Tuesday, have become an increasingly disruptive force in the Middle East in recent years, striking Israel, Saudi Arabia and a global shipping route in solidarity with Iran and allied armed groups.
They have been at war with Yemen's internationally recognized government since 2014, when the rebels swept down from their mountainous heartland and seized much of northern and central Yemen. Saudi Arabia entered the war the following year on behalf of the government.
