The Iraqi army and Sunni tribal fighters have dislodged Islamic State from the al-Waleed border crossing into Syria, an Iraqi military statement said on Saturday.
The capture of al-Waleed removes Islamic State fighters from the vicinity of a U.S. base located on the other side of the border, in Syrian territory.
Aircraft from the U.S.-led coalition and the Iraqi air force took part in the operation, the statement said.
Al-Waleed is close to Tanf, a strategic Syrian border crossing with Iraq on the Baghdad-Damascus highway, where U.S. forces have assisted Syrian rebels trying to recapture territory from Islamic State.
U.S. forces have been based at Tanf since last year, in effect preventing Iranian-backed forces supporting Syrian President Bashar al-Assad from receiving heavy weaponry from Iran by using the main highway between Iraq and Syria.
The involvement of Iraqi Sunni tribal fighters in the operation to dislodge the militants from al-Waleed is another indication that Iran will not yet be able to use the highway.
Pro-Assad forces in Syria, mainly comprising Iraqi Shi'ite militias, last week reached the Iraqi border north-east of Tanf, potentially preventing the U.S.-backed rebels from taking more territory from Islamic State alongside the border area with Iraq.
In Mosul, where a U.S.-backed offensive against Islamic State on Saturday entered its ninth month, the militants have been squeezed into an enclave on the western bank of the Tigris river. Islamic State also controls territory along the border with Syria and urban pockets west and south of Mosul.