ATHENS — Russia’s military is now saying it will “fundamentally” cut back operations near Kiev and a northern city in Ukraine, potentially a significant concession by Moscow amid talks aimed at ending the war that began more than a month ago.

A deputy defense minister, Alexander Fomin, said the move was meant “to increase trust” in talks aimed at ending fighting, as negotiators met face-to-face in Turkey after several rounds of failed negotiations. Not mentioned was that Russia’s troops have been bogged down and struggling to make major advances recently.

The talks in Istanbul this morning, which took place at that city’s iconic Dolmabahçe Palace facing the Bosporus strait, raised flickering hopes there could be progress toward ending a war that has ground into a bloody campaign of attrition.

Mr. Fomin said Moscow had decided to “fundamentally … cut back military activity in the direction of Kyiv and Chernihiv” to “increase mutual trust and create conditions for further negotiations.”

Ukraine’s military said it had noted withdrawals around Kyiv and Chernihiv, though the Pentagon said it could not corroborate the reports.

Turkey’s foreign minister said Russian and Ukrainian negotiators have reached “a consensus and common understanding” on some issues.

Mevlut Cavusoglu said the two sides made “the most meaningful progress” since the start of the negotiations at a meeting in Istanbul on Tuesday. He said the meeting would be followed by one between the Russian and Ukrainian foreign ministers.

After the meeting a key advisor to Ukraine’s president, Mykhailo Podoliak, tweeted that Ukraine wants security guarantees that would see America, Britain, Turkey, France, and Germany ‘’legally involved‘’ in protecting Ukraine from any aggression — an intriguing proposition to which Moscow has not yet formally responded. 

Sanctioned Russian-Israeli oligarch Roman Abramovich was present as an unofficial mediator just a day after it was disclosed he was poisoned at a previous meeting, along with two Ukrainian officials, the Daily Mail reported. Two of Mr. Abramovich’s pricey yachts, now barred from virtually every European port, are said to be docked in Turkish ports.

Ukrainian officials were warned not to eat, drink, or even touch anything during today’s negotiations, and delegates were given bottled water with glasses covered with paper tops, the Daily Mail also reported.  

An adviser to the Ukrainian president said the meeting in Istanbul was focused on securing a cease-fire and guarantees for Ukraine’s security — issues that have been at the heart of previous unsuccessful negotiations.

Ahead of the talks, President Zelensky said his country was prepared to declare its neutrality, as Moscow has demanded, and was open to compromise over the contested eastern region of Donbas — comments that might lend momentum to negotiations. Yet even as the negotiators assembled, Russian forces hit an oil depot in western Ukraine and demolished a government building in the south, with several deaths.

The Turkish president, Recep Tayyip Erdogan, told the two sides that they had a “historic responsibility” to stop the fighting.

“We believe that there will be no losers in a just peace. Prolonging the conflict is not in anyone’s interest,” Mr. Erdogan said, as he greeted the two delegations seated on opposite sides of a long table.

President Putin’s aim of a quick military victory has been thwarted by stiff Ukrainian resistance. Any hope that raised about prospects for an end to the conflict was accompanied by Western skepticism about the Russian leader’s commitment to seeking peace. The British foreign secretary, Liz Truss, said she thought Mr. Putin was “not serious about talks.”

The British Ministry of Defense tweeted this morning: “The illegal and unprovoked invasion of Ukraine is continuing.”

In fighting that has devolved into a back-and-forth stalemate, Ukrainian forces retook Irpin, a key suburb northwest of the capital, Kiev, Mr. Zelensky said late Monday. He warned that Russian troops were regrouping to attempt to take the area back.

With Associated Press