Iraqi fighter jets struck an ISIS position inside Syria on Monday, a day after the Syrian government authorised its neighbour to target the militants at will.
Iraq's Joint Operations Command said F-16s struck a two-storey house in Souseh, close to the border, that was being used as a meeting place for ISIS leaders.
Syrian President Bashar Al Assad on Sunday authorised Iraqi forces to attack ISIS militants inside Syria without waiting for permission from Damascus.
At the same time, Iraq's prime minister hinted at a bigger role for his forces ahead of a planned US pullout from Syria.
Prime Minister Adel Abdul Mahdi said Iraq is seeking to move beyond its current arrangement with Damascus — under which it launches air strikes against ISIS militants in the neighbouring country after getting approval — but did not offer further details.
“There are groups operating in Syria, and Iraq is the best way to deal with this,” he told reporters in reference to ISIS remnants.
Iraqi warplanes and artillery have in the past pounded ISIS positions inside Syria after getting the green light from Syrian authorities. On Sunday, however, Damascus and Baghdad secured an arrangement that will see Iraq conduct air strikes without prior approval, according to the Associated Press.
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The news of the deal came one day after top security officials from Baghdad met Mr Assad in Damascus.
Mr Abdul Mahdi said the Iraqi delegation had visited Damascus to "gain the initiative, not just deal with the consequences" of any future ISIS activity emboldened by the US withdrawal.
"This issue has a lot of complications," he said, referring to President Donald Trump's surprise announcement this month that he will withdraw US forces from Syria.
"If any negative development takes place in Syria it will affect us. We have a 600 km border with Syria and Daesh (ISIS) is there," the prime minister said.
On Saturday Mr Assad received a letter from Mr Abdul Mahdi calling for both countries to co-ordinate in "fighting terrorism."
Iran-backed Iraqi paramilitary forces are already stationed along the Syria border where they act as a buffer against militant incursions into Iraq territory.
Iraqi militias are also operating inside Syria, where they fight alongside Iran-backed pro-government forces, including the Lebanese Hezbollah.
Mr Abdul Mahdi has previously said that about 2,000 ISIS fighters are operating near the border in Syria and trying to cross into Iraq.
ISIS was militarily defeated in Iraq in 2017 but has continued to launch guerrilla-style attacks on security forces in the north of the country.
In Syria, the group commands a small pocket of territory on the eastern banks of the Euphrates River, near the Iraq border.
A US-backed alliance of Kurdish and Arab, the Syrian Democratic Forces, has been battling militants in the area since September while coalition warplanes have killed more than 1,000 ISIS militants, according to the Syrian Observatory for Human Rights.