In a surprise attack on Sunday, fierce battles broke out in Deir Ezzor countryside, east Syria, between Syrian Democratic Forces (SDF) and regime forces, which led to the latter's control of four villages, before SDF succeeded in regaining it backed by Coalition air force.
SDF considered the attack as an "obstruction of the battle it is preparing to liberate the remaining areas under ISIS control."
Meanwhile, Head of Syrian Observatory for Human Rights (SOHR) Rami Abdel Rahman told Agence France-Presse: "The regime's aim is to protect Deir Ezzor city by pushing back SDF fighters from the eastern bank."
Incidents between both sides have occurred in the past, but Abdel Rahman said it was the first time the regime had launched an operation to seize territory from the SDF.
State news agency SANA said the army seized control over four villages in the eastern province, where SDF alliance has been.
After hours of fighting in the region, SDF announced it liberated the villages, while the Observatory said it had recovered three out of the four.
Ahmed Ramdan, an activist of EuphratesPost.com, told Asharq Al-Awsat that Kurdish forces had retrieved most of the villages supported by the Coalition and military reinforcements.
In a statement, SDF asserted the villages had been restored "after the regime and its militias - backed by Russia - launched an attack on our sites in Deir Ezzor countryside" aiming to disrupt operation Island Storm and fight on terrorism. The Forces pointed out to the ongoing attempts of the regime to advance towards the villages.
Military expert Mamoun Abu Nawar, set this attack within the context of the Russian messages to the US, which will continue between the two parties until a solution is found on the Syrian crisis.
He explained to Asharq Al-Awsat that "Moscow's message to Washington is that its presence in this region must come to an end, at a time US preferred not to escalate by not resorting to direct military response, as happened earlier, because the most important goal is to reduce the capabilities and control of the regime."
President of the Center for Kurdish Studies, Nawaf Khalil, agrees with Abu Nawar, and even goes as far to say that the regime's attack would not have happened had it not been approved by Russia.
Speaking to Asharq Al-Awsat Khalil indicated that Moscow is determined not to accept the rules of engagement agreed between Presidents of US and Russia, in order to create more confusion and say that the regime is the only one capable of fighting terrorism.
Earlier on Saturday, the Observatory reported SDF and Coalition alertness in eastern and northern countryside of Deir Ezzor and the southern countryside of al-Hasakah, backed by air alertness witnessed in the area east of the Euphrates River, as part of the preparations for a massive military operation aiming to end ISIS presence in the entire east of the Euphrates River.
SOHR indicated that ISIS is concentrated in an enclave that includes 4 villages and towns on the eastern bank of the Euphrates River which are al-Bahra, Hajin, Abu al-Hassan, Shaafah, al-Baghuz, and the organization is also in the north-eastern countryside of Deir Ezzor, which is connected with the southern countryside of al-Hasakah and includes 22 villages and areas.
Currently, the regime controls Deir Ezzor and the entire West Bank of the Euphrates River, while SDF are deployed on its eastern side.
In February, about 100 pro-regime fighters were killed in strikes by the international coalition in Der Ezzor. Washington confirmed at the time, that the raids were to repel an attack by pro-regime forces targeting the headquarters of the Syrian Democratic Forces.
In September 2017, SDF accused Russia of bombing a site, killing one of its fighters and injuring others.
SDF, mostly formed of Kurdish People's Protection Forces, have controlled much of the area east of Euphrates River in Deir Ezzor since last year, as part of a major campaign that drove ISIS out of east Syria on the Iraqi border.
Regime forces rarely engage with SDF, focusing more on the restoration of land from ISIS west of the river.