Iraq has put F-16 warplanes acquired from the United States into action against the Islamic State (ISIS) group for the first time, the commander of the air force said Sunday, according to AFP.

“Fifteen air strikes were carried out in the past four days,” staff lieutenant general Anwar Hama Amin said following a news conference in Baghdad.

“Smart weapons” were used in the strikes, Amin said, without specifying the type.

Iraq’s Defense Minister, Khaled al-Obaidi, told the news conference that the strikes had achieved “important results” and that the jets will have “an impact on the conduct of operations in the future”.

Amin added that the F-16 strikes had taken place in Salaheddin and Kirkuk provinces, north of Baghdad, according to AFP.

The Pentagon confirmed that Iraq’s air force had gone after ISIS using F-16s.

The first four Iraqi F-16s arrived from the United States in mid-July, out of a total of 36 Washington has agreed to sell to Baghdad.

The purchase had been a source of tension, with Baghdad repeatedly complaining that they have not been delivered quickly enough.

In Washington, Pentagon spokesman Peter Cook said the United States “commend the Iraqi air force for its successful use of this cutting-edge aircraft in the international campaign to degrade and ultimately defeat” ISIS.

“The United States is committed to building a strategic partnership with Iraq and the Iraqi people and we will continue to work with the government of Iraq on the delivery of the remaining aircraft as they become available within the framework of the production schedule,” Cook said, according to AFP.

ISIS declared itself an Islamic “caliphate” last year in swathes of territory it captured in Iraq and Syria.

Since September of last year, the group has been the target of airstrikes in Syria and Iraq by an American-led international coalition.