DAMASCUS, Syria (AP) — Syria's state news agency says President Bashar Assad has authorized Iraqi forces to attack the Islamic State group inside Syria without waiting for permission from authorities in Damascus.

Sunday's announcement highlights the close relations between the two neighboring Arab countries. IS once controlled large parts of both countries when it declared a caliphate in 2014.

Iraqi warplanes and artillery have in the past pounded IS positions inside Syria after getting the green light from Syrian authorities.

The extremists have been defeated in Iraq but still hold a small area in Syria.

On Saturday Assad received a letter from Iraq's Prime Minister Abdul-Mahdi calling for both countries' coordination in "fighting terrorism."

President Donald Trump announced earlier this month that the U.S. will withdraw all of its 2,000 forces in Syria.