Explainer: How Yemen's Houthis went from a small mountain militia to a big regional threat

Key Points:

• Yemen's Houthi group has rapidly advanced to control the strategic Bab el-Mandeb Strait, enhancing their regional influence and ability to disrupt vital shipping routes and Saudi energy infrastructure.
• Originating in the late 1990s as a Zaydi Shi'ite revival movement, the Houthis evolved into a formidable militia with Iranian and Hezbollah support, seizing Yemen's capital in 2014 and engaging in prolonged conflict with a Saudi-led coalition.
• Recent fighting has resumed after a ceasefire collapse, with the Houthis capturing key areas along the Red Sea coast, enabling them to threaten shipping lanes and potentially launch further offensives toward Aden.
• The Houthis have demonstrated advanced missile and drone capabilities, striking targets as far as Israel and frequently attacking Saudi cities, infrastructure, and Red Sea shipping, aided by Iranian-supplied technology and expertise.
• Despite some domestic arms production, the Houthis remain reliant on Iranian support for advanced weaponry and training, with estimates of their fighting force at around 350,000, including underage recruits.