From Yemen to Iraq and through Syria to Lebanon, Iran’s use of local partners has proved consistently effective. What is the current balance of power in the Middle East? In conventional terms it rests overwhelmingly with the West and its allies, whose combined arsenals dwarf those of Iran and its partners. But the more subtle “balance of effective force” — in other words, those capabilities which are most readily deployable and deliver greatest military and political advantage in an actual conflict — has tipped over the last five years decisively toward Iran. Tehran possesses a capability which its adversaries do not: the capability to fight through indigenous third parties.