Syria’s anti-regime forces early on Friday entered Homs city in a week-old lightning advance across northern Syria and a devastating new blow to Bashar Assad.

Syrian opposition forces, led by the Hayat Tahrir al-Sham (HTS), seized control of al-Rastan and Talbiseh after many militants inside both cities joined the ranks of the fighters, said Rami Abdel Rahman, head of the Syrian Observatory for Human Rights, a U.K.-based war monitor.

Abdel Rahman described the battle of Homs as "crucial" because "whoever wins this battle will rule Syria in the future," he said.

Media reports said Assad troops were withdrawing from the city as the anti-regime forces rode into the heart of the city.

Homs is located barely 162 kilometers (100 miles) north of the capital and Assad’s seat of power, Damascus. It also holds strategic importance as it connects to the coastal regions, a longtime redoubt of Assad’s Alawite sect and where his Russian allies have a naval base and air base.

Anti-regime forces have already captured the key cities of Aleppo and Idlib in the north and Hama in the center, dealing devastating blows to Assad’s regime, nearly 14 years after protests against him erupted across Syria.

Assad regained control of most of Syria after his key allies – Russia, Iran and Lebanon's Hezbollah group – offered support. But all have recently been diverted by other crises, giving anti-regime groups a window to fight back.

‘Your time has come’

Opposition forces had pledged to move on to the central city of Homs.

"Your time has come," said an opposition operations room in an online post, calling on Homs residents to rise up in revolution.

HTS leader Abu Mohamed al-Joulani has said the goal is to overthrow Assad and form a new government.

"The seeds of the regime's defeat have always been within it," al-Joulani told the U.S. broadcaster CNN. The Iranians and Russians had tried to revive it but he said, "The truth remains: This regime is dead."

Iran will send missiles, drones and more advisers to Syria, a senior Iranian official said Friday. Hezbollah, meanwhile, sent a small number of "supervising forces" from Lebanon to Syria overnight to help prevent anti-regime fighters from seizing Homs, two senior Lebanese security sources told Reuters.

A Syrian military officer and two regional officials close to Tehran also told Reuters that elite forces from Iran-backed Hezbollah had crossed from Lebanon overnight and had taken up positions in Homs.

Homs emptying

A resident of Homs said the offices of Syria's main security branches there were emptied on Friday morning, with members leaving the city.

The Observatory said thousands of people had begun fleeing Homs on Thursday night toward Syria's western coastal regions.

Wasim Marouh, a Homs resident who decided not to leave, said most of its main commercial streets were empty, while pro-regime militia groups patrolled the streets.

Meanwhile, Syrian regime forces shelled the city of Talbiseh, though there is no information yet on casualties, Abdel Rahman reported.

Activists in Homs' northern countryside told Deutsche Presse-Agentur (dpa) that opposition factions are now on the verge of gaining full control of the area.

On Friday morning, Israeli airstrikes hit two border crossings between Lebanon and Syria, Lebanon's Transport Minister Ali Hamieh said.

The strikes hit just across the border on the Syrian side of both the Arida crossing in northern Lebanon and the Jousieh crossing, which links to eastern Lebanon, Hamieh said, both important access points to Homs.

Russian bombing overnight also destroyed the Rastan bridge along the key M5 highway to prevent anti-regime fighters from using this main route to Homs, a Syrian regime officer told Reuters.

280,000 Syrians displaced

The escalation in fighting in Syria has displaced around 280,000 people in just over a week, the United Nations said on Friday, warning that numbers could swell to 1.5 million.

"The figure we have in front of us is 280,000 people since Nov. 27," Samer AbdelJaber, head of emergency coordination at the U.N.'s World Food Programme (WFP), told reporters in Geneva.

"That does not include the figure of people who fled from Lebanon during the recent escalations" in fighting there, he added.

Shaken legitimacy

Until last week, the war in Syria had been mostly dormant for several years, but analysts have said the violence was bound to flare up as it was never truly resolved.

Bashar Assad is under growing strain as his army suffers setbacks, the economy deteriorates, his support wanes and his regime’s foreign backers are focused elsewhere.

The rapid fall of Aleppo has shaken Assad's legitimacy and emboldened his opponents, analysts said.

While Damascus remains heavily fortified, and the regime forces launched counterattacks with Russian air support, the loss of Homs, an important hub on the way to the capital, is crucial.

Ankara summons Astana

Türkiye on Friday confirmed it would meet Russia and Iran in Doha on Saturday for talks on the escalating civil war.

Türkiye, Russia and Iran have regularly held talks on Syria's future in a trilateral format as part of what is known as the Astana peace process. While Russia and Iran support Assad, NATO member Türkiye backs the political and armed opposition.

Since the start of the renewed conflict, Ankara has called on Assad to engage with the Syrian people for a political solution. It has denied any involvement in the HTS-led operation and said it did not want to see a new migrant wave heading toward its borders.

Ankara backs the Syrian opposition forces that captured Tal Rifaat from the PKK terrorist group's Syrian wing YPG; however, the HTS is recognized as a terrorist group.

President Recep Tayyip Erdoğan on Friday said he hoped the Syrian anti-regime fighters would continue their advances "without any incidents or disasters."

"Idlib, Hama, Homs and the target, of course, is Damascus. The opposition's march continues. Our wish is that this march in Syria continues without accidents or disasters," Erdoğan told reporters following Friday prayers in Istanbul.

The president also expressed frustration over Syria's leadership, saying: "We made a call to Assad. We said: 'Come, let's determine the future of Syria together.' Unfortunately, we did not receive a positive response to this."

Although Türkiye severed ties with Assad’s regime when the civil war broke out in 2011, Ankara supports the territorial integrity of the country. The sides made a push last year to mend ties and Erdoğan over the summer voiced a plan to invite Assad for talks.

The Syrian regime leader briefly floated the possibility of reviving Turkish-Syrian relations, claiming the withdrawal of Turkish troops from Syria was not a precondition for talks, but no progress followed.