The Palestinian movement Hamas on Wednesday said it restored relations with the Syrian government after a visiting delegation met with President Bashar al-Assad in Damascus.
The Islamist group, which controls the Gaza Strip, was long one of Syria's closest allies, in large part because of a shared enmity toward Israel.
But Hamas left Syria in 2012 after condemning the Assad government's brutal suppression of protests in March 2011, which triggered the country's descent into civil war.
"This is a glorious and important day, in which we come back to our dear Syria to resume joint work," Hamas chief of Arab relations Khalil al-Hayya told reporters in Damascus.
"This is a new start for joint Palestinian-Syrian action," he said after meeting Assad along with other representatives of Palestinian factions.
Hamas and Assad have agreed to "move on from the past and look to the future," al-Hayya added.
Al-Hayya said there was consensus among Hamas leadership and supporters over the resumption of ties with Syria, a move also supported by the Palestinian group's foreign sponsors.
"All the states we notified of our decision were welcoming and supportive of the move, including Qatar and Turkey, who encouraged us to take the step," al-Hayya said.
The Syrian presidency said Assad met a delegation of Palestinian leaders without mentioning the restoration of ties with Hamas.
But the presidency published a video of Assad and al-Hayya holding hands as they walked with other Palestinian officials.
The two-day Hamas visit to Syria comes after the Islamist group signed a reconciliation deal with its Palestinian rival Fatah in Algiers last week, vowing to hold elections by next October in a bid to settle a 15-year intra-Palestinian rift.
A Hamas leader told AFP that the group, which was headquartered in the Syrian capital before leaving the country, plans to reopen its Damascus office.
But it was too early to talk about relocating its headquarters to the Syrian capital, said the official who spoke on the condition of anonymity.
The thaw between Hamas and Damascus was brokered by Tehran and Hezbollah, a senior Hamas source said.
Hamas has its origins in the transnational Muslim Brotherhood, whose Syrian branch was one of the leading factions in the armed opposition after Syria's civil war broke out.
Hamas officials have said they broke ties with the Brotherhood in 2017.
