BAGHDAD — Iraq’s parliament approved a new government headed by Haider al-Abadi as prime minister on Monday night, in a bid to rescue Iraq from collapse, with sectarianism and Arab-Kurdish tensions on the rise.

Abadi, a Shi’a Islamist, included members of Iraq’s Shi’ite majority and its Kurdish and Sunni minorities in his cabinet as he started his uphill task to unify the country after this summer’s devastating loss of territory across northern Iraq to “Islamic State” fighters.

Adel Abdel Mehdi from the Islamic Supreme Council of Iraq was named oil minister, while Ibrahim Jafaari, a former premier, was named foreign minister. Rowsch Shaways, a Kurd, was named finance minister. No interior or defense minister was named, but Abadi pledged to do so within a week, bringing the cabinet to 37 posts. 

Abadi’s deputy prime ministers are Hoshiyar Zebari, a Kurd and Iraq’s only post-Saddam Hussein foreign minister; Saleh Mutlaq, a secular Sunni Muslim who served in the same position in the last government; and Baha Arraji, a Shi’a Islamist and former lawmaker. 

The parliament approved for the ceremonial posts of vice presidents the last prime minister, Nuri al-Maliki, like Abadi from the Shi’a Islamist Dawa party; former premier Iyad Allawi, a secular Shi’a; and the last parliament speaker Usama al-Nujaifi. The three have been seen as political rivals.

Abadi looked ahead to unifying the country and defeating “Islamic State.”

He vowed to “allow all people in Iraq to participate in liberating the cities and provinces which have been taken over by terrorist groups.. and to bring back security and stability.”

The prime minister warned: “Any armed formation outside the authority of the state is banned.”

However, Abadi was careful in referencing the sensibilities of his Shi’a majority sect, which feels it is fighting for its survival against “Islamic State.”

Abadi saluted the network of Shi’a militias and ordinary citizens, called volunteers, who mobilized this summer to stop “Islamic State” fighters from marching on Baghdad. The groups have become controversial, with Sunni political figures and tribal leaders accusing them of turning ordinary Sunni citizens.

Looking to the future, Abadi proposed that volunteers should be incorporated into “a national guard organization.”

He vowed to rebuild the Iraqi army, which nearly collapsed this summer in the face of “Islamic State’s” march across northern Iraq. And he promised to work to improve Baghdad’s thorny relationship with Iraqi Kurdistan. He also said he would push a program of decentralization.

On Wednesday U.S. Secretary of State John Kerry visited Baghdad and endorsed a new power-sharing government for Iraq, led by Abadi.

Kerry called Abadi’s new government “the heart and backbone” of the fight against Islamic State.