The military councils of the Syrian Democratic Forces (SDF) declared Monday general mobilization in areas under their control in northeastern Syria.
They also announced sending military reinforcements near the borders with Turkey as Ankara continues to threaten to wage a new offensive in the region.
The Syrian Observatory for Human Rights reported the arrival of new regime reinforcements to the frontlines in the Manbij countryside, east of Aleppo.
Several buses loaded with regime and Russian forces arrived at frontlines on Monday.
Pro-Turkish National Army factions in the Manbij countryside also took up positions.
The regime forces have recently reinforced their positions in Ain Issa and the M4 international highway.
The reinforcements comprised buses transporting 250 soldiers, five tanks and heavy weapons.
The area witnesses almost daily clashes between the warring parties.
Separately, masses of US soldiers roamed the Tal Tamr countryside, northwest of al-Hasakah governorate, under the protection of SDF patrols.
The International Coalition Forces and SDF carried out a new round of military drills using live ammunition at the coalition base in al-Shaddadi town, south of al-Hasakah.
A convoy of military aid, comprised of 50 trucks, also arrived at the base. It included weapons, logistic equipment, armored vehicles and water and fuel tanks.
A day earlier, 80 trucks carrying reinforcements arrived at Coalition bases in al-Hasakah and the Deir Ezzor province.