JERUSALEM—The capture of significant portions of Aleppo, Syria’s second-largest city, by extremist Islamist forces presents a serious challenge to U.S. policy in Syria.

Jason Brodsky, policy director for United Against Nuclear Iran, expressed concern over the potential seizure of sensitive sites, including the Syrian Scientific Studies and Research Center, which houses Assad’s chemical weapons program. He highlighted the groups’ past affiliations with Al-Qaeda, raising concerns about the implications for Israeli national security.

The Israeli government reportedly held an emergency meeting Friday night to discuss the situation.

The 2013 deal between President Obama and Bashar al-Assad to remove chemical weapons was widely criticized, with reports suggesting Assad retained portions of his chemical warfare arsenal. Assad has repeatedly used chemical weapons against his own people since the 2011 uprising.

Approximately 900 U.S. soldiers are currently in Syria, aiming to defeat ISIS and counter Iranian influence.

The takeover of Aleppo, a city of two million, represents a significant setback for Assad, Hezbollah, Russia, and Iran.

However, Brodsky cautioned that Hayʼat Tahrir al-Sham (HTS), the group responsible for the Aleppo victory, is also a dangerous organization designated by the U.S. as a foreign terrorist group. He suggested that Israel’s weakening of Hezbollah may have emboldened anti-Assad forces.

“Let’s not forget that Israel decapitated the IRGC Quds Force Department 2000, which oversees operations in the Levant, twice in the last year alone, not to mention other key commanders in the Syrian theater. That is a loss of relationships, skills and networks that have placed the IRGC at a disadvantage, especially when Hezbollah has been under such strain,” he stated.

Both Iran and Syria are U.S.-designated state sponsors of terrorism.

Phillip Smyth of the Atlantic Council noted that most successful offensives supporting Assad since 2013 (Iran) and 2015 (Russia) relied heavily on Iranian and Russian forces.

Smyth described HTS as an Al-Qaeda offshoot with ties to Turkey, aiming to establish a Taliban-like society. He doubted the U.S. would condone this given Al-Qaeda’s role in 9/11, but also recognized Assad’s anti-American stance and his support of Hezbollah and other jihadist groups as equally concerning.

The Syrian Democratic Forces (SDF), a U.S.-allied Kurdish coalition, also has a presence in Aleppo and played a key role in defeating ISIS.

Wladimir van Wilgenburg, a Kurdish studies expert, highlighted the presence of Kurdish-dominated neighborhoods in Aleppo controlled by the SDF/YPG, along with displaced people from Afrin. He anticipated conflict between HTS and the YPG over control of the airport, noting recent Russian airstrikes in Aleppo.

Van Wilgenburg further emphasized the threat HTS poses to the YPG’s presence in northern Aleppo, citing the YPG/SDF’s withdrawal from Nubl and Zahra.

General Hossein Daghighi of the IRGC stated that resistance networks are well-organized and that attempts to interfere in Syria will be met with decisive force.

The Syrian regime announced a “redeployment operation” in Aleppo, citing the large number of terrorists and multiple battlefronts. They stated that dozens of soldiers were killed or wounded, and that terrorist organizations gained control of large parts of Aleppo.

Assad’s regime is responsible for the deaths of over 500,000 people in Syria since 2011, a toll the UN has stopped tracking.