A U.N.-released photo of the ancient city of Palmyra in Syria before it fell into the hands of the Islamic State. (Ron Van Oers/AP)

Syrian troops backed by Russian air power on Thursday appeared close to storming Islamic State-held Palmyra, an ancient city whose capture by the extremist group in May shocked the world.

Retaking the desert city would represent a significant victory for Russia’s military intervention in the conflict in support of President Bashar al-Assad, a longtime ally.

Syrian state media reported that ground forces have advanced past the outskirts of Palmyra, a UNESCO World Heritage Site about 150 miles northeast of the capital, Damascus. The Islamic State has destroyed several of the city’s Roman-era monuments.

State television said troops have battled their way inside the city, although the Syrian Observatory for Human Rights, a Britain-based monitoring group, said fighting is still at the edges.

The Islamic State’s Amaq News Agency, however, released a video purporting to show quiet in Palmyra, including empty streets. The group “will deter their assault,” a fighter shown sitting on top of a tank says in the video, which was translated by the SITE Intelligence Group.

Meanwhile, Secretary of State John F. Kerry met with Russian President Vladimir Putin at the Kremlin to discuss a political transition for Syria that the Obama administration has said must result in Assad’s exit from power. Putin has firmly pushed back against such a scenario.

“We agreed on a time schedule to establish a framework for a political transition and also a draft constitution, all of which we target by August,” Kerry said at a news conference with Russian Foreign Minister Sergei Lavrov.

Earlier in the day, Kerry and Lavrov praised a mutually backed cease-fire agreement that took hold in Syria on Feb. 27. That truce excludes the Islamic State and has held despite numerous violations reported by each side, helping to reduce violence in a war that has killed more than 250,000 people and uprooted millions.

Putin thanked Kerry and President Obama for their support in achieving progress in finding a resolution to the conflict in Syria.

In Geneva, U.N. envoy Staffan de Mistura concluded nearly two weeks of what he described as “very serious” discussions with the Syrian government and opposition representatives over the “principles” that will guide the political transition that he said would be the topic of talks scheduled to resume early next month.

De Mistura presented both sides with a 12-point document of what he called “points of commonalities” between them. They included Syrian territorial integrity within its current borders as a democratic and non-sectarian state, equal rights for women, the return to their homes of all displaced people, the release of those “arbitrarily” detained, and continuity of state institutions, including the Syrian military.

The Syrian government said it would study the document. An opposition representative in Geneva told reporters that the discussions “have perhaps laid the basis for substantive talks at the next round . . . that will lead us directly into discussions about the political transition.”

So far, the two sides have spoken only in “proximity,” gathering in separate rooms while de Mistura and his team shuttle between them.

Although de Mistura acknowledged that the talks had not moved into substance — including Assad’s future — he indicated that their lasting this long without collapsing should be considered progress, along with the continuation of the now four-week-old cease-fire and delivery of humanitarian aid. “There have been no breakdowns, no walkouts, no personal delegitimization,” de Mistura told reporters.

“What I would tell the Syrian people is, you’re right in having doubts. You have been waiting five years, you have been disappointed so many times, you have been suffering much more than anyone could expect from any people,” he said.

“But please, look at the facts. Would you ever have dreamed just five months ago that countries like the United States and Russia would actually seriously sit and engage in serious talks” about Syria?

In Palmyra, pro-government forces have faced tough resistance from Islamic State fighters. As many as 40 militants and nine soldiers have been killed during clashes in the area in the past 24 hours, the Observatory said.

The official Syrian Arab News Agency published pictures of soldiers flashing peace signs as they purportedly prepared to battle over the city.

Palmyra’s recapture would help Russia bolster its stated narrative of intervening in Syria to fight the Islamic State. The United States and Syrian rebels groups say that Moscow’s air raids have targeted mostly anti-Assad groups other than the Islamic State.

Despite Putin’s decision this month to draw down his forces in Syria, a number of Russian warplanes have remained and continue to carry out raids. Since September, Russian has conducted a blistering number of airstrikes in Syria, inflicting heavy damage on rebel forces.

Capturing Palmyra may have longer-term benefits for Syria’s government. Controlling the area would bring Assad’s forces closer to retaking oil infrastructure in the country’s east that is controlled by the Islamic State.

But fighting in Palmyra would threaten to inflict yet more damage to the city’s cherished, 2,000-year-old ruins. Many already have been blown up by the militant group, including the 1st-century Temple of Bel.

In August, the group beheaded the city’s former chief of antiquities and hanged his body from a Roman column.

The group regularly targets pre-Islamic artifacts and other symbols of multiculturalism.

Andrew Roth in Moscow and Karen DeYoung in Washington contributed to this report.

Read more:

Palmyra’s Temple of Bel withstood 2,000 years of war and invasions — until the Islamic State

Why the ancient city of Palmyra, seized by the Islamic State, matters

The Islamic State has lost more than a fifth of its territory, says report

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