BEIRUT (AP) — The leader of Syria’s most powerful insurgent group toured the seized city of Aleppo on Wednesday in a surprise visit — the first since the group captured large parts of the city over the weekend as fierce fighting intensifies in the government-led counter-offensive in northern Hama.

Abu Mohammed al-Golani, who heads the jihadi group Hayat Tahrir al-Sham, greeted crowds of supporters near the city’s iconic citadel as he smiled and waved in dark green military garb. Surrounded by masked gunmen in flak jackets, men and boys chanted “God is great” as he walked through the heart of Syria’s largest city.

The sudden capture of Aleppo, also an ancient business hub, was a stunning prize for Syrian opponents of President Bashar Assad.

It was the first opposition attack on the city since 2016, when a brutal Russian air campaign retook the northwestern city for Assad after rebel forces had initially seized it. Intervention by Russia, Iran and Iranian-allied militant Hezbollah and other groups has allowed Assad to remain in power.

The latest flareup in Syria’s long civil war comes after forces opposed to Assad ousted his troops from Aleppo and seized towns and villages in southern parts of the northwestern Idlib province, likely exploiting the fact that Assad’s main regional and international backers were preoccupied with their own wars.

The offensive is being led by the jihadi HTS as well as an umbrella group of Turkish-backed Syrian militias called the Syrian National Army. For years, both have entrenched themselves in northwest Idlib province and parts of northern Aleppo, as the battered country reeled from years of political and military stalemates.

The war between Assad and his foreign backers and the array of armed opposition forces seeking his overthrow has killed an estimated half-million people over the past 13 years.

Elsewhere, Syrian authorities said their counteroffensive pushed back insurgents attempting to advance to the strategic central city of Hama, while the insurgents said they captured more Syrian troops and Iran-backed militants in fierce battles.

Syrian state SANA news agency on Wednesday said insurgents retreated some 20 kilometers (12 miles) from government-held Hama, Syria’s fourth-largest city, as government troops backed by Russian airpower entrenched themselves in the outskirts. Fierce fighting has raged for days as Damascus fears that the insurgents will make their way into Hama as they did over the weekend into Aleppo.