The months-long standoff in Iraq between Sunni Arab protesters and the central government has begun a perilous, downward slide toward confrontation. The emergence of an arc of instability and conflict linking Lebanon, Syria and Iraq, fuelled by sectarianism and involving porous borders as well as cross-border alliances, represents a huge risk. Failure to integrate Sunni Arabs into a genuinely representative political system in Baghdad risks turning Iraq’s domestic crisis into a broader regional struggle.