BAGHDAD — Special forces teams and army tanks surrounded the Green Zone housing Iraq's government as Prime Minister Nouri al-Maliki fiercely clung to power Sunday, taking the stability of the country to the brink at a moment when it is already facing a lethal challenge from radical Islamist fighters.
In actions that had all the markings of a political coup, al-Maliki gave a defiant late-night speech in Baghdad saying he would lodge a legal case against Iraq's president, who has resisted naming him as the candidate for another term as prime minister.
Tanks rumbled onto major bridges and roads in the capital as security forces were put on high alert, with militiamen also patrolling Shiite neighborhoods. The special forces teams surrounding the Green Zone were taking orders directly from the prime minister, security officials said.
Al-Maliki's critics blame him for overseeing the de facto fragmentation of the country, with extremists from the Sunni-dominated Islamic State of Iraq and Syria marauding through territory in the north and west and threatening Baghdad. The critics say al-Maliki, a Shiite, has persecuted and alienated members of the Sunni minority, driving them into the arms of radical groups.
The United States began airstrikes in northern Iraq on Friday as ISIS threatened previously stable Kurdish territory, sending thousands of minority Christians and Yazidis fleeing for their lives.
But President Barack Obama has established limited goals in the air operation, linking further assistance to the formation of a new government in Baghdad that is more inclusive of the country's Sunnis.
The U.S. government indicated Sunday evening that it had broken with al-Maliki. State Department spokeswoman Jen Psaki said in a statement that "the United States fully supports President Fouad Massoum in his role as guarantor of the Iraqi Constitution. We reaffirm our support for a process to select a prime minister who can represent the aspirations of the Iraqi people by building a national consensus and governing in an inclusive manner. We reject any effort to achieve outcomes through coercion or manipulation of the constitutional or judicial process."
The latest crisis came on a day when Kurdish forces expelled ISIS extremists from two northern Iraqi towns, Makhmour and al-Gweir, in the first signs of a turnaround for the embattled Kurds after a week of stunning losses to the militants. Their success came in the wake of U.S. airstrikes on the towns.
But the political standoff raised the prospect of deeper turmoil and potentially new violence in Iraq, where Shiite militias that had battled U.S. troops during the war have re-established themselves in recent months.
Al-Malikii's political rivals, the country's religious authorities and even parts of his political bloc have tried unsuccessfully to persuade him to step aside. But over his eight years in office, the prime minister has consolidated enormous power in his hands. He is commander in chief of the armed forces, and he holds the Defense and Interior ministry portfolios.
The prime minister's political bloc won the largest share of seats in April's parliamentary elections but not a majority. In his speech, he charged that Iraq's president had violated the constitution by not asking al-Maliki's political bloc to put forward its candidate before a deadline last week.
Al-Maliki's surprise move came at the end of a day that had offered some hope for parts of the country besieged by ISIS warriors. For the third day, U.S. jets and drones swooped over the militants, launching five strikes near Irbil, the Kurdish capital, that damaged and destroyed the group's vehicles and a mortar position, according to the U.S. military.
The airstrikes have given a morale boost to beleaguered Kurdish forces in the semi-autonomous north. They have been battling ISIS militants for two months with outdated weapons, limited ammunition and no salaries.
The Obama administration has said the airstrikes have a limited mission: to protect U.S. military and diplomatic personnel in Irbil, to prevent the massacre of religious minorities, and to safeguard critical infrastructure. On Sunday, thousands of Yazidis, members of a tiny religious sect, fled a barren mountain where they had been trapped for a week, surrounded by the extremist fighters. Some Yazidis said the U.S. airstrikes had helped their escape.