Close to Euphrates river in Iraq's restive Anbar province, Al Qaim crossing faces Al BuKamal in Syria's vast eastern region of Deir Ezzor and was recaptured from Daesh in November 2017.
Iraq reopened its Qaim border-crossing with Syria on Monday after eight years of closure amid regional turmoil, in the latest sign of normalisation between Baghdad and Damascus and also seen a win for their mutual ally Iran.
The opening of the crossing signified "the victory of the Iraqi and Syrian people over all terrorist groups, especially Daesh," said Mohammad Khaled al Rahmoun, Syrian regime interior minister.
It would revitalise Syrian-Iraqi economic cooperation, said Iraqi border authority chief Khadhim al Ikabi, who like Rahmoun was attending a ceremony with local governors of provinces on both sides of the border, a Reuters news agency journalist said.
The western Anbar province town of Qaim, 300 km west of Baghdad was recaptured from Daesh in November 2017 and was the group's last bastion in Iraq to fall.
It borders the Syrian town of Albukamal, which was also a Daesh stronghold.
The towns lie on a strategic supply route and the crossing between them had only been open for regime or military traffic since 2011.
The Syrian regime, with strong backing from Iran-backed militias captured Albukamal on the Euphrates River from Daesh towards the end of 2017.
The Iraqi side of the border had seen the deployment in large numbers of Iran-allied Iraqi Shia militias known as the Popular Mobilisation Forces (PMF) who now de facto control large stretches of the frontier, with posts not far from military bases housing US troops.
The PMF will take part in securing the crossing, a security source in Qaim told Reuters.
Syrian territory across from Albukamal on the eastern side of the river is held by the US-backed Syrian Democratic Forces (SDF) militants.
The positioning of Iran's allies on both sides of the border and within close proximity to the US and allied forces further raises tensions between Washington and Tehran who have been locked in a tense standoff over the latter's nuclear programme and regional activities.
Tensions escalated after the US withdrew last year from a 2015 nuclear deal and reinstated sanctions against Tehran.
On the Syrian side, the border crossing was decorated with Syrian flags and portraits of regime leader Bashar al Assad, footage broadcast by regime-run TV station Al Ikhbariya showed.
The opening of the crossing was a "historic day" for Iraq and Syria, Ali Faris, a local politician, told the station, adding that there would be "great economic and social" consequences.
Daesh in 2014 seized vast swathes of land in both Iraq and Syria, declaring a caliphate across both countries. Iraq declared victory over the group in 2017 and it lost its last territory in Syria earlier this year.
Iraq recently called for the reinstatement of Syria's membership of the Arab League, which was suspended in 2011 over its crackdown on protesters at the start of the civil war.