For decades, the Shiite Muslim ayatollahs who came to power in Iran through the 1979 Islamic Revolution have worked to build an arc of like-minded proxy forces across the Middle East.

Training and arming extremist, nonstate militia groups throughout the region have been pillars of Iran’s foreign and security policy. What the Islamic Republic calls the “Axis of Resistance,” others often describe as a “Shiite Crescent” that stretches from Yemen on the southern Arabian Peninsula through Iraq, Syria and Lebanon, and back down to the Gaza Strip.

Hamas, which controls the strip and is a rare Sunni Muslim organization among mostly Shiite militants, catapulted Iran and its allies back onto the global radar on Oct. 7 with a brutal cross-border attack on Israel. In response, Israel launched a blockade and a sustained bombing campaign that has devastated Gaza, as well as preparations for a possible ground invasion, sparking rumblings about a regional conflagration.

The degree to which Iran holds direct influence over this loose regional network is murky. Here is a summary of the main proxy forces and their locations in the region.

LEBANON

Hezbollah, Arabic for the “Party of God,” emerged in the 1980s from the chaos of Lebanon’s long civil war to become one of the most powerful forces in the region.