The Syrian army on Thursday acknowledged they lost control of the key city of Hama in the central part of the country following reports that rebels led by the Islamist group Hayat Tahrir al-Sham had broken through government defenses.

The latest victory by the jihadis group known as HST came days after their forces seized Aleppo, Syria’s second-largest city, as part of their lightning advance that began a week ago. Hama is located between Aleppo and President Bashar Assad’s power base in Syria’s capital, Damascus.

Syrian military officials said their troops had been holding back “violent and successive attacks” on Hama by HST forces for several days. On Thursday, the insurgents reportedly had managed to fight their way into the city despite taking heavy losses.

“To preserve the lives of the civilians of the city of Hamas and not get involved in the battles inside the city, the military units associated with it have repurposed and deployed outside the city,” the Syrian Defense Ministry said on its Facebook page.

Video circulating online Thursday appeared to confirm that the insurgent forces had captured a government military airport outside Hama, freeing prisoners held in a detention facility there.

Ambassador Robert Wood, the alternate U.S representative at the United Nations, said the Biden administration has been closely following the unfolding situation in Syria. The Assad government, with the military backing of both Iran and Russia, had appeared to have the clear upper hand in the country’s 13-year-old civil war until the events of the past week.

Mr. Wood said the rebels appeared to take advantage of the government’s complacency and the fact that its key supporters were distracted by wars of their own.

“For many years the Syrian government has been engaged in a civil war backed by Iran, Russia and Hezbollah. All three of those actors have recently been distracted and weakened by conflicts elsewhere,” Mr. Wood said this week in an address at the U.N. “It is no surprise that we have seen actors in Syria try to take advantage of that over the past several days.”

The Biden administration has long opposed and tried to isolate the Assad regime, but has also expressed concerns about the insurgent forces and their possible links to radical Islamist groups.

Hayat Tahrir al-Sham, designated as a terrorist organization by the U.S. and other countries, launched its offensive in northern Syria on November 27. It was the same day a ceasefire took effect in neighboring Lebanon between Israel and Hezbollah.

Russia, while preoccupied with its war in Ukraine, also expressed alarm at recent events in Syria.

Dmitry Peskov, the chief Kremlin spokesman, said Moscow was “closely monitoring” the rebels’ stunning advances in recent days.

“Depending on the assessment of the situation, we will be able to talk about the degree of assistance that is needed by the Syrian authorities to cope with the militants and eliminate this threat,” Mr. Peskov said.

• Mike Glenn can be reached at mglenn@washingtontimes.com.