Ukraine-Russia peace talks to resume in Istanbul after surprise drone attack

LONDON -- Ukrainian and Russian delegations are set to meet again in Istanbul, Turkey, on Monday to take part in the next round of U.S.-brokered peace talks intended to end Russia's 3-year-old invasion of its neighbor.

Revived talks so far have failed to reach a peace deal, or even achieve a sustained ceasefire, despite pressure on both sides by President Donald Trump's administration. The last meeting between Russian and Ukrainian delegations in Istanbul in mid-May was the first direct contact between the two sides since spring 2022.

Secretary of State Marco Rubio spoke with Russian Foreign Minister Sergei Lavrov on Sunday, according to a readout published by the State Department -- which said the call took place "at Russia's request."

"Secretary Rubio reiterated President Trump's call for continued direct talks between Russia and Ukraine to achieve a lasting peace," the State Department said.

The Russian Foreign Ministry said in a statement that the two men "exchanged views on various initiatives concerning the political settlement of the Ukrainian crisis."

Ukraine is calling for a full 30-day ceasefire during which time peace negotiations can take place. Russia has refused the request, with President Vladimir Putin and his top officials retaining maximalist war goals dating back to the opening days of the Russian invasion.

Among the Kremlin's demands are the annexation of four Ukrainian regions -- plus the retention of Crimea, which Russia seized in 2014 -- Ukrainian demilitarization and a permanent block on the country's accession to NATO.

Ukrainian President Volodymyr Zelenskyy said in a Sunday social media post that Kyiv's delegation will be led by Defense Minister Rustem Umerov.

The president set out Ukraine's goals for the meeting. "First -- a full and unconditional ceasefire," he wrote. "Second -- the release of prisoners. Third -- the return of abducted children. And in order to establish a reliable and lasting peace and ensure security, preparation of the meeting at the highest level."

Zelenskyy and his government have repeatedly accused Putin of intentionally sabotaging peace talks since Trump returned to office in January, having promised on the campaign trail to end the war within 24 hours. Trump's threat of further sanctions on Russia do not appear to have softened the Kremlin's war goals.

Zelenskyy and his European backers have pushed Trump to increase pressure on Putin by introducing new sanctions on Russia and providing Ukraine with more military support. Keith Kellogg, Trump's Ukraine-Russia envoy, hinted at the president's growing frustration with Moscow, telling ABC News last week that the president has "seen a level of unreasonableness that really frustrates him."

In a phone conversation with Trump in May, Putin said Russia would provide a "peace memorandum" outlining a possible settlement. Moscow is yet to provide the document. Vladimir Medinsky -- a Putin aide and long-time member of Russia's negotiating team -- said Sunday that the Russian team had received Ukraine's version of the peace memorandum.

Since the last round of talks in Istanbul, Trump has hit out at Putin -- calling him "absolutely crazy" -- and again criticized Zelenskyy, saying of the Ukrainian leader, "Everything out of his mouth causes problems, I don’t like it, and it better stop."

Oleksandr Merezhko, a member of the Ukrainian parliament representing Zelenskyy's party and the chair of the body's foreign affairs committee, told ABC News, "Russia's primary goal is to avoid sanctions by pretending that it negotiates."

"Putin is not interested in negotiations and ceasefire, because he hopes to start an offensive during summer," Merezhko added.

"On the one hand, he imitates negotiations to avoid Trump's sanctions and simultaneously to demonstrate that Russia is not politically isolated. Yet, on the other hand, Putin hopes that if Trump will decide to withdraw from the negotiations, he will leave Ukraine without military support, one-on-one with Russia."

The talks come a day after Ukraine launched one of the most stunning attacks of the war. In what a source in the Security Service of Ukraine (SBU) told ABC News was an operation one and a half years in the making, operatives used attack drones concealed in containers carried by trucks to attack strategic bomber bases deep inside Russian territory.

Moscow has used long-range bombers and their cruise missile armaments to attack Ukrainian cities throughout the full-scale invasion. The SBU claimed to have hit more than 40 military aircraft in the attacks, which targeted multiple air bases thousands of miles from Ukrainian-controlled territory.

Russia's Defense Ministry framed the operation as "a terrorist attack," claiming that the strikes were "repelled" in three regions, but noting that several aircraft caught fire at airfields during the attacks in Irkutsk and Murmansk -- videos of which the SBU published.

Also on Sunday, Russian authorities reported the collapse of two railway bridges and derailment of two trains in regions bordering Ukraine, which they blamed on "explosions." At least seven people were killed, authorities said.

In an address on Sunday, Zelenskyy called the Ukrainian drone attack a "brilliant operation" and said Russia "suffered truly significant losses." The president framed the attack as a defensive measure.

"We will defend ourselves by all means available to us," Zelenskyy said. "Not for a single second did we want this war. We offered the Russians a ceasefire. Since March 11, the U.S. proposal for a full and unconditional ceasefire has been on the table. It was the Russians who chose to continue the war."

"Pressure is truly needed -- pressure on Russia that should bring it back to reality," Zelenskyy added. "Pressure through sanctions. Pressure from our forces. Pressure through diplomacy. All of it must work together."

Meanwhile, long-range drone and missile attacks continued overnight into Monday morning.

Ukraine's air force said Russia launched 80 drones and four missiles into the country overnight, of which 52 were shot down or neutralized. The air force reported impacts in 12 locations.

Russia's Defense Ministry said it shot down 162 Ukrainian drones over nine Russian regions overnight.

ABC News' Ellie Kaufman contributed to this report.