The modern Middle East has always been divided against itself. But for the first time the emerging lines of cleavage are sectarian—Shia versus Sunni—threatening to make the region’s regimes more unstable, its conflicts more intractable and its nationalism more infused with Islamic fervor.
Before World War II, the main lines of cleavage in the Middle East were the product of imperial rivalries between Britain and France. During the early Cold War decades, revolutionary regimes aligned with the Soviet Union clashed against conservative monarchies aligned with the West. Next, a theocratic Iran posed the main threat to the status quo, challenging a secular brand of Arab nationalism with an Islamic variant. And throughout the post-World War II era the Palestine-Israel dispute has remained an enduring fault line.
The strategic landscape of the Middle East is changing yet again as the emergence of a “Shia Crescent” running from Tehran to Beirut awakens a new sectarian divide. This earthquake began with America’s invasion of Iraq, a move that installed a Shia regime in Baghdad and effectively triggered a civil war among Shia, Sunnis and Kurds.
Buoyed by the power shift in Iraq as well as its rising oil revenues, Iran's theocratic government is reveling in the Shia resurgence and pursuing a more muscular regional diplomacy. The war in Lebanon has further heightened sectarian tensions, once again dividing the country along religious lines and putting Iran-backed Hezbollah at the helm of the anti-Israel cause.