What Happened to ISIS? U.S. and Syria Near Total Victory Over Jihadis, but May Turn on Each Other Next

The Syrian military and the U.S.-backed Syrian Democratic Forces have announced sweeping gains against the Islamic State militant group (ISIS) in the last of its major hideouts in eastern Syria. The two rival anti-jihadi campaigns, however, now risk turning against one another.

The Syrian Army and Armed Forces General Command issued Wednesday a statement declaring the clearing of up to 2,240 square miles of the desert region, known as the Syrian Badiya, from ISIS control. The military hailed the latest in a series of nationwide victories against the jihadis, who have suffered "heavy losses of life and equipment," and vowed to continue fighting until the entire nation was free of takfiri ideology, a term used to describe groups such as ISIS that brand other Muslims to be infidels for not adhering to their ultraconservative strain of religious thought.

"In the face of the persistence of the men of our brave army and their devastating blows, ISIS strongholds and headquarters and in the places to which they spread across various axes and fronts to the administrative borders of Homs province have collapsed, and those remaining from the terrorist takfiri gangs have fled," the statement said.

"The cleansing of this vast area of the Syrian Badiya, reaching the Iraqi border, and the crushing of the terrorist organization in that region confirms the high efficiency of the Syrian Arab fighter and the persistence of the Army and Armed Forces General Command in continuing to pursue the remnants of the armed terrorist organizations of different names until security, peace and stability prevail. The entire Syrian territory is being cleansed along its geography from the filth of takfiri terrorism and its regional and international supporters," the statement continued.

Members of the pro-Syrian government forces pose with portraits of Syrian President Bashar al-Assad and his late father, Hafez al-Assad, as they gather in a public square in the Syrian border town of Al-Bukamal after retaking it from ISIS, on November 20, 2017. Syrian victories in Al-Bukamal and Deir Ezzor were hailed by the government as the end of ISIS. STRINGER/AFP/Getty Images

The Syrian campaign has been heavily bolstered by Russian air power and support from Iran, which backs a number of mostly Shiite Muslim militias battling alongside Syrian troops. Moscow and Tehran played a crucial role in helping Syrian President Bashar al-Assad retain power after he was threatened by a 2011 uprising backed by the U.S., Turkey and Gulf Arab states, such as Saudi Arabia and Qatar.

U.S. support for the rebels dried up, however, as jihadi groups began to dominate the opposition and ISIS spread from neighboring Iraq, where the 2003 U.S. invasion gave rise to a powerful Sunni Muslim insurgency. The U.S. established a coalition of friendly powers in 2014 and began bombing ISIS in Iraq and Syria. In September 2015, Russia entered the conflict to back Assad and Iranian allies and, the following month, the Pentagon officially began supporting a majority-Kurd faction known as the Syrian Democratic Forces.

Related: Who is U.S. fighting in Syria? 'Hostile force' attacks coalition near base condemned by Russia and Iran

Since then, the Syrian military—backed by Russia, Iran and various pro-government militias—and the Syrian Democratic Forces—supported by the U.S.-led coalition—have largely defeated the jihadis who once claimed half the country. The Syrian Democratic Forces Press Office released Tuesday a report detailing its own gains against ISIS on the eastern banks of the Euphrates River that divides the two offensives against the jihadis, saying the campaign "succeeded in liberating the entire town of Al-Dashisha and its villages and farms with an area of 600 km2 [about 232 square miles] as of 24/6/2018."

Citing the Operations Room General Command for the campaign known as Island Storm, referring to the massive jazeera, or "island," territory surrounded by the Euphrates and Tigris Rivers, the report also said the Syrian Democratic Forces had dismantled mines and killed up to 274 ISIS fighters and emirs, inflicting "heavy losses" on weapons and equipment as well.

U.S.-led coalition forces fire an M777 Howitzer at an outpost near Al-Dashisha, Syria, on June 9. The U.S.-backed Syrian Democratic Forces restarted anti-ISIS operations last month after scores of Kurdish fighters fled to battle Turkey and Syrian rebels earlier this year in northwestern Syria. Army Staff Sergeant Timothy R. Koster/Department of Defense

Due to dueling Syrian military and Syrian Democratic Forces, the jihadi presence there in the Syrian Desert and Euphrates River Valley is quickly shrinking. While Kurdish militias of the Syrian Democratic Forces have shown a willingness to work with pro-Syrian government fighters against certain rebel groups and Turkish forces, the U.S.-backed alliance has also increasingly clashed with forces fighting on behalf of Assad.

Last week, deadly airstrikes killed a number of pro-Syrian government fighters—including Iraq militias—in the eastern province of Deir Ezzor, a once ISIS-held region now split by Syrian government and the Syrian Democratic Forces control. The state-run Syrian Arab News Agency and the Iran-backed Popular Mobilization Forces battling ISIS under the umbrella of the Iraqi military both blamed the U.S.-led coalition, which denied responsibility. Unnamed U.S. officials cited in CNN and Agence France-Presse pointed the blame to Israel, which has struck Iranian and pro-Iran assets in Syria with greater frequency in recent months.

Days later, the U.S.-led coalition told Newsweek it came under fire from an "unidentified hostile force" in the southern Syrian Desert region of Al-Tanf, located near the country's borders with Iraq and Syria. The U.S. has maintained a roughly 34-mile deconfliction zone around a base established in Al-Tanf and has repeatedly fired on pro-Syrian government forces that have attempted to enter.

Syria, Russia and Iran have accused the U.S. of using the area to maintain a long-term military presence in the country and of shielding terrorist organizations, something the U.S. has denied. Syria considers Russia and Iran to be legitimate partners in the battle against rebels and jihadis, but has called on the U.S. and Turkey to withdraw immediately.