From the pro-CIA Cipher Brief

This network of Iranian proxies in Iraq, Syria, Yemen, Lebanon, Bahrain, and possibly elsewhere is what makes Tehran so deadly in the region. It’s a clever method of power projection, honed over decades, because it allows the Iranians to weaken their adversaries and achieve their strategic aims with the fewest costs possible. Iran will fight to the last Iraqi, Syrian, Yemeni, Lebanese, and Bahraini. The Iranians have every intention of continuing to rely on their indirect approach because it has paid strategic dividends.

Source: How Iran is Winning, One Attack at a Time