Russia pounded Ukraine’s southern cities with drones and missiles for a third consecutive night Thursday, keeping Odessa in the Kremlin’s crosshairs after a bitter dispute over the end of a wartime deal that allowed Ukraine to send grain through the key Black Sea port.

The strikes killed at least two people at Odessa. At Mykolaiv, a city close to the Black Sea, at least 19 people were injured, including a child, Ukrainian officials said.

Russia has targeted critical Ukrainian grain export infrastructure since it vowed “retribution” this week for an attack that damaged a crucial bridge between Russia and the Moscow-annexed Crimean Peninsula. Russian officials blamed that strike on Ukrainian drones.

The strikes on Ukraine’s grain export infrastructure have helped drive up food prices in countries facing hunger issues. THe UN secretary-general, Antonio Guterres, said the end of the deal would result in more human suffering, with potentially millions of people affected.

The grain deal provided guarantees that ships would not be attacked entering and leaving Ukrainian ports, while a separate agreement facilitated the movement of Russian food and fertilizer.

The Russian military on Thursday described its strikes on Odessa, a city whose downtown area is described by the UN’s cultural agency as possessing “outstanding universal value,” as “retaliatory.”

In January, Unesco added Odessa’s historic center to its list of endangered World Heritage Sites, with the group’s director-general, Audrey Azoulay, saying the “legendary port” has “left its mark in cinema, literature, and the arts.”

Despite multiple Russian artillery attacks and airstrikes during the war that began in February 2022, Odessa had not previously been subjected to the heavy barrages that have targeted other towns and cities in Ukraine’s south and east.

The Russian defense ministry said in a statement that it targeted “production shops and storage sites for unmanned boats” in Odessa and the nearby city of Chornomorsk. In the Mykolaiv area, the Russian military claimed to have destroyed Ukraine’s fuel infrastructure facilities and ammunition depots.

Neither sides’ claims could be independently verified.

The previous night, an intense Russian bombardment using drones and missiles damaged critical port infrastructure in Odessa, including grain and oil terminals. The attack destroyed at least 60,000 tons of grain.

In what appeared to be a tit-for-tat move, Ukraine’s defense ministry announced that as of Friday, all vessels in the Black Sea heading to Russian ports “may be considered by Ukraine as such carrying military cargo with all the associated risks.” That may result in higher insurance costs for those ships.

Russia’s defense ministry said earlier this week that Moscow had formally declared wide areas of the Black Sea dangerous for shipping and warned that it would view any incoming ship as laden with weapons, effectively announcing a sea blockade.

The European Union’s foreign affairs chief condemned Russia’s targeting of grain storage facilities.

“More than 60,000 tons of grain has been burned,” Josep Borrell said in Brussels on Thursday, regarding Moscow’s recent tactics. “So not only they withdraw from the grain agreement … but they are burning the grain.”

The German foreign affairs minister, Annalena Baerbock, said at the same meeting that the EU is involved in international efforts to get Ukrainian grain to the world market.

“The fact that the Russian president has canceled the grain agreement and is now bombing the port of Odessa is not only another attack on Ukraine, but an attack on the people, on the poorest people in the world,” she said. “Hundreds of thousands of people, not to say millions, urgently need grain from Ukraine.”

The White House warned Wednesday that Russia was preparing possible attacks on civilian shipping vessels in the Black Sea. The warning could alarm shippers and further drive up grain prices.

Russia has laid additional sea mines in the approaches to Ukrainian ports, the White House National Security Council spokesman, Adam Hodge, said in a statement. “We believe that this is a coordinated effort to justify any attacks against civilian ships in the Black Sea and lay blame on Ukraine for these attacks,” the statement said.

Meanwhile, Russia has been exporting record amounts of wheat in recent months despite complaints that its agricultural exports have been hindered.

Also on Thursday, in the Russian-annexed territory of Crimea, “an enemy drone” — an apparent reference to Ukraine — attacked a settlement in the peninsula’s northwest, the region’s Moscow-appointed governor, Sergei Aksyonov, stated. He said the attack damaged several administrative buildings and killed a teenage girl.