It was described as a “powder keg” moment. In late May, just across the Tigris river from Baghdad’s fortified Green Zone, a heavily armed convoy of American forces was driving down a street near the Iraqi Interior Ministry.

Iraq’s parliament went into summer recess for a month on Monday after political leaders failed to agree on a series of laws that Washington sees as crucial to stabilizing the country.

US Secretary of State Condoleezza Rice has warned that Iran poses the biggest threat to US Middle East interests, as she begins a major regional tour.