The US has carried out its first air strike against Islamic State (IS) militants under a new strategy to "degrade and destroy" the group.
US officials said the strike destroyed an IS fighting position near Baghdad, five days after President Obama outlined his new anti-IS strategy.
IS has seized large areas of Syria and Iraq and declared a "caliphate".
Meanwhile, Iraq's new PM saw his two nominations for defence and interior minister rejected by parliament.
The rejections of the two key posts are a setback for Prime Minister Haider al-Abadi.
The US has also been building a broad coalition to fight the jihadist group, which is also known as Isil or Isis.
US Central Command said Monday's strike was "the first taken as part of our expanded efforts beyond protecting our own people and humanitarian missions".
It did not specify the exact location, but Iraqi security spokesman Lt Gen Qassem Atta told AFP news agency it was "an important strike" in Sadr al-Yusufiya, 25km (15 miles) from the capital.
In northern Iraq, Kurdish "peshmerga" forces backed by US surveillance jets and drones have been advancing against IS positions, the BBC's Jim Muir reports.
An attack into the IS-held plain of Mosul, east of the city, began at dawn while on the other side of Mosul, the Kurds have also been pressing towards the town of Zumar, our correspondent says.
Iraq's Prime Minister Haider al-Abadi, who has already had most of his cabinet approved, presented his nominees for the unfilled roles of defence and interior minister to parliament on Tuesday.
He nominated Jabir al-Jabri from the Sunni National Forces Alliance for the defence minister and the Shia politician Riyad Gharib as interior minister.
However, both nominees failed to secure enough votes for approval in parliament, which will reconvene again on Thursday to reconsider the posts.
The US also said an IS position near the north-western town of Sinjar had been targeted on Sunday, destroying six IS vehicles.
The strikes are a change in tactics for the US, which had previously carried out strikes in Iraq to protect US interests and personnel, help Iraqi refugees and secure infrastructure.
In total, US fighter planes have conducted more than 160 air strikes across Iraq since August.
In a speech last week, President Obama unveiled a four-point plan to defeat IS using air strikes, support for Iraqi troops, anti-terrorism activities and humanitarian aid.
He has said there are no plans to send in US ground troops.