KYIV, Ukraine — A Russian rocket attack targeted the northeastern Ukrainian city of Sumy on Tuesday, killing at least four people and wounding 25, officials said. President Volodymyr Zelenskyy denounced the assault, saying it underscored that Moscow has no intentions of halting the 3-year-old war.

The attack came a day after direct peace talks in Istanbul made no progress on ending the fighting. Local authorities said the barrage of rockets struck apartment buildings and a medical facility in the center of Sumy.

Meanwhile, Ukraine’s secret services said they struck inside Russia again, two days after a spectacular Ukrainian drone attack on air bases deep inside the country.

The Ukrainian Security Service, known by its acronym SBU, claimed it damaged the foundations of the Kerch Bridge linking Russia and illegally annexed Crimea — a key artery for Russian military supplies in the war.

The SBU said it detonated 2,400 pounds of explosives on the seabed overnight, in an operation that took several months to set up. It was the third Ukrainian strike on the bridge since Russia’s invasion of its neighbor in February 2022, the SBU said.

“The bridge is now effectively in an emergency condition,” the SBU claimed.

The agency said no civilians were killed or injured in the operation. It was not possible to independently confirm those claims.

Traffic across the Kerch Bridge was halted for three hours early Tuesday, but it reopened at 9 a.m., official Russian social media channels said. It closed for a second time at 3:20 p.m. and reopened again after two and a half hours.

The Ukrainian president called the attack on Sumy a “completely deliberate” strike on civilians.

“That’s all you need to know about Russia’s ‘desire’ to end this war,” the Ukrainian president wrote on social media.

Zelenskyy appealed for global pressure and “decisive action from the United States, Europe and everyone in the world who holds power.” Without it, he said, Russian President Vladimir Putin “will not agree even to a ceasefire.”

The war has killed more than 12,000 Ukrainian civilians, according to the United Nations, as well as tens of thousands of soldiers on both sides along the roughly 620-mile front line where the fighting grinds on despite U.S.-led efforts to broker a peace deal.

Though Russia has a bigger army and more economic resources than Ukraine, the Ukrainian drone attack over the weekend damaged or destroyed more than 40 warplanes at air bases deep inside Russia, Ukrainian officials said, touting it as a serious blow to the Kremlin’s strategic arsenal and military prestige.

The Russian Defense Ministry acknowledged that the Ukrainian attack set several planes ablaze at two air bases but said the military repelled attempted attacks on three other air bases.

Both Zelenskyy and Putin have been eager to show U.S. President Donald Trump that they share his ambition to end the fighting — and avoid possible punitive measures from Washington. Ukraine has accepted a U.S.-proposed ceasefire, but the Kremlin effectively rejected it. Putin has made it clear that any peace settlement has to be on his terms.