US and Ukrainian officials have met for further talks aimed at hammering out a ceasefire in Russia’s war in Ukraine, with Washington signalling its hope for “real progress” even as Moscow warned that “difficult negotiations” lie ahead.

The gulf in expectations marked the start of the latest round of negotiations in Saudi Arabia, which was set to follow with a meeting between American officials and Russia on Monday. The US is pushing for a broad ceasefire in Russia’s war in Ukraine by 20 April, according to Bloomberg, though sources said the timeline may slip given the wide gap that exists between Kyiv and Moscow’s positions.

On Sunday, the US special envoy, Steve Witkoff, appeared upbeat about working with the Russian president, Vladimir Putin, to end Europe’s deadliest conflict since the second world war. “I feel that he wants peace,” Witkoff told Fox News.

This week’s talks are expected to delve into the details of implementing the 30-day ceasefire on energy infrastructure, and potentially expand into shipping in the Black Sea.

“I think you’re going to see in Saudi Arabia on Monday some real progress, particularly as it affects a Black Sea ceasefire on ships between both countries,” said Witkoff. “And from that you’ll naturally gravitate to a full-on shooting ceasefire.”

Ukraine’s defence minister, Rustem Umerov, said after the meeting that the talks were “constructive”, adding that the energy sector was a key focus of the negotiations.

“The discussion was productive and focused – we addressed key points including energy,” he said on social media, adding Ukraine was working to make its goal of a “just and lasting peace” a reality.

Earlier on Sunday, the White House national security adviser, Mike Waltz, said that the US was also talking through a range of confidence-building measures, including the future of Ukrainian children taken into Russia.

The Kremlin, however, swiftly poured cold water on hopes for a rapid resolution, saying that “difficult negotiations” lie ahead. “We are only at the beginning of this path,” Kremlin spokesperson Dmitry Peskov told Russian state TV on Sunday.

Peskov said the “main” focus in its talks with the US would be a possible resumption of a 2022 Black Sea grain deal, brokered by Turkey and the UN, that ensured safe navigation for Ukrainian farm exports via the Black Sea.

Moscow pulled out of the deal in 2023, amid accusations that the west had failed to uphold its commitments to ease sanctions on Russia’s exports of farm produce and fertilisers.

Speaking to Fox News on Sunday, Witkoff, a real estate developer who had no prior diplomatic experience before being tasked as Donald Trump’s special envoy, downplayed fears of Vladimir Putin launching a broader aggression.

“I just don’t see that he wants to take all of Europe,” he said. “I take him at his word in this sense, so, and I think the Europeans are beginning to come to that belief, too. But it sort of doesn’t matter. That’s an academic issue … The agenda is, stop the killing, stop the carnage. Let’s end this thing.”

Last week Putin agreed to Trump’s proposal for a 30-day halt on attacks to energy infrastructure. The ceasefire, however, was cast into doubt soon after, with both sides reporting continued strikes.

Ukrainian officials said on Sunday that at least seven people were killed overnight after Russia launched 147 drones. Ukrainian air defences shot down 97 of the drones, and 25 others were hindered by Ukrainian countermeasures.

Three people, including a five-year-old child, were killed in Kyiv, while four people were killed in Russian attacks on Ukraine’s Donetsk region.

Russian troops reportedly seized the small village of Sribne in Ukraine’s eastern Donetsk region, while Ukraine’s army said its troops had recaptured the small village of Nadia in the eastern Luhansk region.

Russian officials said Sunday that their air defences had destroyed 59 Ukrainian drones targeting the country’s southwestern regions, noting that the strikes had killed one person in Rostov.

This week’s talks come on the heels of a wide-ranging interview with the former Fox News host, Tucker Carlson, in which Witkoff detailed his admiration for Putin, who launched the full-scale invasion of Ukraine three years ago, and scorned the UK’s prime minister.

Witkoff said he “liked” the Russian president – “I don’t regard Putin as a bad guy … He’s super smart”, he said – while he dismissed Keir Starmer’s readiness to put British troops on the ground in Ukraine post-ceasefire as “a combination of a posture and a pose”.

Witkoff, who is leading the US ceasefire negotiations with both Russia and Ukraine, described Starmer’s idea as “simplistic” adding: “I think there’s this, you know, this sort of notion of we’ve all got to be like Winston Churchill, the Russians are gonna march across Europe. I think that’s preposterous. By the way, we have something called Nato that we did not have in World War II.”

Witkoff also asserted that Kyiv had “agreed” to hold elections, though he offered no further details or backing for the claim. Ukraine’s constitution bars national elections from being held during a period of martial law, while, logistically speaking, any outcome risks being marred by disruptions from air raids, potential attacks on crowded polling stations and the Russian occupation of some regions.

When asked about the upcoming talks, however, Witkoff said the “central issue” was the Ukrainian regions that had been annexed or partially occupied by Russian forces. He stumbled, however, in trying to name them.

“The largest issue in that conflict are these so-called four regions, Donbas, Crimea, you know the names and there are two others,” said Witkoff, in remarks that appeared to be an attempt to name Luhansk, Donetsk, Zaporizhzhia and Kherson and that confused Crimea for one of the four occupied eastern territories.

Earlier this month, Volodymyr Zelenskyy stressed that Ukraine would not recognise any occupied territories – where Russia was accused of holding sham polls in 2022 in a bid to provide cover for their illegal annexation – as Russian.

Witkoff appeared to side with the Kremlin as he cited the largely discredited polls as evidence of local sentiment on the ground and conflated the locally spoken language with support for Russia.

“They’re Russian-speaking,” Witkoff said of the four eastern regions. “There have been referendums where the overwhelming majority of the people have indicated that they want to be under Russian rule.”

In 2022, the Organisation for Security and Cooperation in Europe, which monitors elections, said the referendums had not met international standards and had been held in areas where much of the population had fled and which were not secure, while there has been no evidence to suggest that Russian-speaking areas are more favourable to Russian rule.

Witkoff continued: “The Russians are de facto in control of these territories. The question is: will the world acknowledge that those are Russian territories? Can Zelenskyy survive politically if he acknowledges this?”

Witkoff, who met Putin earlier this month in Moscow, told Carlson that the meeting “got personal”, as Putin had commissioned “a beautiful portrait” of Trump from a “leading Russian artist” for Witkoff to take home to the US president.

Putin also told Witkoff of his reaction to the failed assassination attempt against Trump. “He went to his local church and met with his priest and prayed for the president – not because he was the president of the United States or could become the president of the United States – but because he had a friendship with him and he was praying for his friend,” said Witkoff.

“And I came home and delivered that message to our president and delivered the painting, and he was clearly touched by it,” he added.

His comments were swiftly slammed by the journalist and historian Anne Applebaum. “If you ever wondered how the KGB manipulated foreigners and got them to repeat Soviet propaganda, spend some time listening to Steve Witkoff talk about his wonderful conversations with Vladimir Putin,” she wrote on social media.

Witkoff went on to assert that the Russians had now obtained what they had hoped for when they launched the full-scale invasion of Ukraine. “Why would they want to absorb Ukraine? For what purpose, exactly? They don’t need to absorb Ukraine,” he said. “They’ve gotten – they’ve reclaimed these five regions. They have Crimea, and they’ve gotten what they want. So why do they need more?”

Instead he envisioned a global stage where the US and Russia could build on the ceasefire to normalise relations and join forces in areas such as energy policies in the Arctic, sea lanes, LNG supplies to Europe and artificial intelligence. “Who doesn’t want to have a world where Russia and the United States are doing, collaboratively, good things together?” he asked.