Ukrainian officials reported shelling around the capital Kyiv and the northern region of Chernihiv on Wednesday, despite a promise by Moscow to scale down military operations there.

Russian forces were also shelling nearly all cities along the front line separating Ukrainian government-controlled territory from areas held by Russian-backed separatists in the eastern Donetsk region, the regional governor said, and heavy fighting was reported in the southern port city of Mariupol.

Oleksiy Arestovych, an adviser to President Volodymyr Zelenskyy, said Russia was transferring forces from northern Ukraine to eastern areas trying to encircle the Ukrainian troops there. He said Russia would keep some troops near Kyiv to try to prevent Ukrainian forces from reinforcing the eastern front.

"Although the Russians are withdrawing some troops from (around) Kyiv, they will still leave certain forces here (near Kyiv) to keep our troops here," Arestovych said in televised comments. Kyiv's Deputy Mayor Mykola Povoroznyk told national television that the capital itself had not been shelled overnight.

"The night passed relatively calmly, to the sounds of sirens and the sound of gunfire from battles around the city, but there was no shelling in the city itself," he said.

Ukrainian authorities said Wednesday that Russian forces had bombarded the northern city of Chernihiv.

"The enemy has demonstrated its 'decrease in activity' in the Chernigiv region with strikes on Nizhyn, including airstrikes. Chernihiv was shelled all night," Regional Governor Vyacheslav Chaus wrote on social media. "Do we believe in it (the promise to reduce military activities)? Of course not," Chaus wrote on the Telegram messaging app.

The governor of the Khmelnytskyi region in western Ukraine said Russian forces had hit industrial facilities in the region in three strikes overnight.

Governor Serhiy Hamaliy gave no details of the targets or the damage, but said fires had been "localized" and checks were being made to determine whether there were any casualties.

Arestovych said street fighting in Mariupol was heavy and half the city had been taken by Russian forces.

Vitaliy Kim, governor of the Mykolayiv region in southern Ukraine, said fighting also continued around occupied Kherson on the Black Sea and in the region as a whole.

"We are not relaxing, we are working on strengthening our defense capability," Kim said.

Russia's pledge to scale back some military operations in Ukraine drew skepticism, a bitter reality check in a rare moment of optimism five weeks into what has devolved into a bloody war of attrition. Zelenskyy said that there was no reason to believe Russia's announcement that it would reduce military activity near Kyiv as well as in the northern city of Chernihiv, given what's happening on the ground.

"We can call those signals that we hear at the negotiations positive," he said in his nightly video address to the Ukrainian people. "But those signals don’t silence the explosions of Russian shells."

Still, Tuesday's talks sketched out what could end up being a framework for ending the war that has imposed an increasingly punishing toll, with thousands dead and almost 4 million Ukrainians fleeing the country. The talks had been expected to resume on Wednesday, but with what Turkish Foreign Minister Mevlüt Çavuşoğlu called "meaningful" progress made, the two sides decided to return home for consultations.

At the conference in Istanbul, Ukraine’s delegation laid a framework under which the country would declare itself neutral and its security would be guaranteed by an array of other nations.

Russian Deputy Defense Minister Alexander Fomin said Moscow would in the meantime "fundamentally ... cut back military activity in the direction of Kyiv and Chernihiv" to "increase mutual trust and create conditions for further negotiations."

He did not spell out what that would mean in practical terms.

Russian delegation head Vladimir Medinsky said negotiators would take Ukraine's proposals to Russian President Vladimir Putin and then Moscow would provide a response, but he did not say when.

Çavuşoğlu said he expected a meeting between the Russian and Ukrainian foreign ministers at an unspecified time. Another between the presidents of the two countries is also "on the agenda," he said. Russian state news agency Tass reported that Moscow's delegates arrived back in Russia late Tuesday.

In the wake of the flurry of proposals and some muted optimism, Zelenskyy warned the world and his own people not to get ahead of themselves. He said Ukrainian troops had forced Russia’s hand, adding that "we shouldn’t let down our guard" because the invading army can still carry out attacks.

"Ukrainians are not naive people," he said. "Ukrainians have already learned during the 34 days of the invasion and during the past eight years of war in the Donbass that you can trust only concrete results."

While Moscow portrayed it as a goodwill gesture, its ground troops have become bogged down and taken heavy losses in their attempts to seize Kyiv and other cities. Last week and again on Tuesday, the Kremlin seemed to lower its war aims, saying its "main goal" is gaining control of the mostly Russian-speaking Donbass region in eastern Ukraine.

"We judge the Russian military machine by its actions, not just its words," British Deputy Prime Minister Dominic Raab told Sky News on Wednesday. "There’s obviously some skepticism that it will regroup to attack again rather than seriously engaging in diplomacy."

He added that "of course, the door to diplomacy will always be left ajar, but I don’t think you can trust what is coming out of the mouth of Putin’s war machine."

Britain's Defense Ministry said Wednesday that Russia stating a focus on Donetsk and Luhansk in the Donbass region "is likely a tacit admission that it is struggling to sustain more than one significant axis of advance."

"Russian units suffering heavy losses have been forced to return to Belarus and Russia to reorganize and supply," the ministry said in a statement. "Such activity is placing further pressure on Russia's already strained logistics and demonstrates the difficulties Russia is having reorganizing its units in the forward areas within Ukraine."

It noted that the shift is unlikely to mean relief for civilians in cities suffering relentless Russian bombardments, saying that it expects Moscow will "continue to compensate for its reduced ground maneuver capability through mass artillery and missile strikes."

U.S. President Joe Biden asked whether the Russian announcement was a sign of progress in the talks or an attempt by Moscow to buy time to continue its assault. He said: "We’ll see. I don’t read anything into it until I see what their actions are."

U.S. Secretary of State Antony Blinken suggested Russian indications of a pullback could be an attempt by Moscow to "deceive people and deflect attention."

It wouldn't be the first time. In the tense buildup to the invasion, the Russian military announced some units were loading equipment onto rail cars and preparing to return to their home bases after completing exercises. At the time, Putin was signaling interest in diplomacy. But 10 days later, Russia launched its invasion.

Western officials say Moscow is now reinforcing troops in the Donbass in a bid to encircle Ukraine’s forces. And Russia's deadly siege in the south continues, with civilians trapped in the ruins of Mariupol and other devastated cities. The latest satellite imagery from commercial provider Maxar Technologies showed hundreds of people waiting outside a grocery store amid reports of food and water shortages.

"There is what Russia says and there is what Russia does, and we’re focused on the latter," Blinken said in Morocco. "And what Russia is doing is the continued brutalization of Ukraine."

Even as negotiators gathered, Putin's forces blasted a gaping hole in a nine-story government administration building in a strike on the southern port city of Mykolaiv, killing at least 12 people, emergency authorities said. The search for more bodies in the rubble continued.

"It’s terrible. They waited for people to go to work" before striking the building, said regional governor Kim. "I overslept. I’m lucky."

Pentagon spokesperson John Kirby said the U.S. has detected small numbers of Russian ground forces moving away from the Kyiv area, but it appeared to be a repositioning of forces, "not a real withdrawal."

He said it was too soon to say how extensive the Russian movements may be or where the troops will be repositioned.

The meeting in Istanbul was the first time negotiators from Russia and Ukraine talked face-to-face in two weeks. Earlier talks were held in person in Belarus or by video.

Among other things, the Kremlin has demanded all along that Ukraine drop any hope of joining NATO.

Ukraine’s delegation offered a detailed framework for a peace deal under which a neutral Ukraine's security would be guaranteed by a group of third countries, including the U.S., Britain, France, Turkey, China and Poland, in an arrangement similar to NATO’s "an attack on one is an attack on all" principle.

Ukraine said it would also be willing to hold talks over a 15-year period on the future of the Crimean Peninsula, seized by Russia in 2014.

Medinsky said on Russian TV that the Ukrainian proposals are a "step to meet us halfway, a clearly positive fact."

He cautioned that the parties are still far from reaching an agreement, but said: "We know now how to move further toward compromise. We aren’t just marking time in talks."