(CNN)Syria's long and messy civil war just got more complicated.
Adding to the country's many rival factions, a new alliance appears to have been forged between pro-government forces and Kurdish militias.
Forces loyal to the Syrian government will be deployed to the Kurdish-held region of Afrin "within hours" to help defend a month-long offensive by Turkey, the Syrian official news agency, SANA, said Monday.
The move appears to be the result of an agreement between the Syrian regime and Kurdish forces in Afrin.
The groups are expected to unite against a Turkish offensive launched last month against the People's Protection Units (YPG) in Afrin. Ankara views the YPG as a terrorist group linked to a Kurdish insurgency inside Turkey.
But further complicating matters, the YPG is also the backbone of the United States-backed Syrian Democratic Forces (SDF), who were critical in the war against ISIS in Syria.
If reports of the deal are confirmed, it would mean that allies of the US will be fighting alongside allies of President Bashar al-Assad's regime, which the US opposes.
It was not immediately clear where or what type of forces the Syrian regime is deploying. Kurdish official Badran Jia Kurd said "army troops" would be deployed along the border based on an agreement between Damascus and Syrian Kurdish fighters, Reuters reported Sunday.
YPG officials refused to comment on the purported deal when contacted by CNN.
What is happening in Afrin?
Afrin has borne the brunt of Turkey's attacks since January 20, when Ankara launched Operation Olive Branch to remove Kurdistan Workers' Party (PKK), Kurdish Democratic Union Party (PYD) and ISIS militants from the area along its border.
The military operations have predominately targeted the YPG.
Turkey sees the quest by the Kurds -- who are spread out in Turkey, Syria, Iran and Iraq -- to establish an independent homeland as an existential threat to its territorial integrity. And Turkey has long warned that it will not tolerate YPG control of much of its border with Syria.
An estimated 16,000 people have been displaced by the fighting, which has been punctuated by relentless airstrikes and shelling, according to the United Nations.
US and Turkey: A complicated relationship
Turkey's operation in Afrin has also raised tension between the United States and its NATO ally because Washington supports YPG fighters in the battle against ISIS in Syria.
While the US does not support groups in Afrin, they are linked to American allies elsewhere in Syria.
A US announcement in mid-January that it would form a 30,000-strong Kurdish-led border force in northeastern Syria also sparked this heightened period of US-Turkey tension.