Explosions thundered above Odesa, Ukraine, as Russia targeted it with missiles and drones before dawn on Tuesday, a day after an apparent Ukrainian strike damaged an important Russian bridge and the Kremlin halted a deal for safe passage of grain ships on the Black Sea.
Moscow suggested that the unusual barrage aimed at Odesa, Ukraine’s largest port, was in response to the attack on the strategic Kerch Strait Bridge, which links Russia to the Russian-occupied Crimean Peninsula. Kyiv had asserted it was related to the grain deal, which the Kremlin denied.
But even so, Russia delivered an ominous warning about any attempts to ship Ukrainian foodstuffs, which are vital to global supplies, from Ukrainian ports now that Russia no longer agrees to exempt them from a naval blockade, which it imposed after invading Ukraine 17 months ago.
“We are talking about a zone that is very close to the area of armed hostilities,” Dmitri S. Peskov, the Kremlin spokesman, told journalists. “Certain risks emerge there without appropriate security guarantees. Therefore, if something will get formalized without Russia’s participation, these risks need to be considered.”
The bridge that was struck is both a vital road and rail link for Russian forces, fighting in southern Ukraine, and a pet project of President Vladimir V. Putin, who directed its construction after ordering the illegal seizure of Crimea in 2014 and on Monday vowed retribution.
The attack was made with two Ukrainian naval drones, Russian officials said, but while Ukrainian officials have reveled in the news they stopped short of claiming responsibility. Ukraine has made no secret of its efforts to build a formidable fleet of surface and underwater unmanned vessels, and Vasyl Maliuk, the head of the Security Service of Ukraine, said that the bridge was a legitimate target.
The Institute for the Study of War, a Washington-based organization, said that the assault, though less damaging than a truck bombing of the same bridge in October, would “likely have continuing ramifications on Russian logistics in southern Ukraine.”
The Russian Defense Ministry, in a statement on Telegram, said on Tuesday that in Odesa and nearby sites it had carried out a “mass retaliatory strike with precision sea-based weapons, against facilities where terrorist acts against Russian troops were prepared using unmanned boats,” a shipyard where the drones were made and other targets, including fuel storage facilities.
As usual, the two sides gave drastically different accounts of the results. The Ukrainian military said it had shot down all six cruise missiles fired at Odesa by Russian ships, as well as 21 drones launched from Crimea, though the aerial detonations and missile debris caused some damage to port infrastructure and homes.
The Russian military said: “All the targets planned for the strike were hit. Fires and detonation at the destroyed facilities were recorded.”
Though Russia has demonstrated that it can strike in any corner of Ukraine, major attacks aimed at a city as far from the front lines as Odesa, on the southwestern edge of Ukraine’s coastline, have been rare. The Ukrainian military said Russia launched drones at other cities, as well, including the port of Mykolaiv, and that in all 31 of 36 were intercepted.
Russia, in turn, claimed to have shot down a barrage of Ukrainian drones aimed at Crimea.
Ukrainian officials said the strikes on Odesa were meant to send a message that Moscow would use food and hunger as weapons to hold the world ransom. “The world must realize that Russia’s goal is to starve and kill people,” said Andriy Yermak, the head of President Volodymyr Zelensky’s office.
Russia and Ukraine are major food exporters, but for the first months after the full-scale invasion began last year, the blockade of Ukrainian ports and Western sanctions against Russia combined to sharply lower global grain and cooking oil supplies — raising prices and creating a crisis in parts of Africa. The lack of exports also stifled a large part of the Ukrainian economy.
The Black Sea Grain Initiative, brokered last summer by the United Nations and Turkey, allowed shipments from Ukraine to resume, subject to Russian inspection. It also contained steps to enable Russian food and fertilizer exports, but Moscow repeatedly said those provisions were inadequate or were not being honored, and threatened to withdraw. On Monday, it finally did so.
The United Nations says the agreement enabled almost 33 million tons of food to leave Ukraine by ship in less than a year.
Grain prices have not changed much this week, and economists say Russia’s exit from the deal will not have the dire effects seen last year, in part because other parts of the world have had robust harvests and in part because Ukraine has stepped up exports by truck, train and river barge.
In an overnight speech, Mr. Zelensky said that he had sent letters to the U.N. secretary general and the president of Turkey, proposing that Ukraine continue to ship exports that he called “necessary for everyone in the world.” That would risk a military conflict at sea with Russia.
“The only thing that is needed now is its careful implementation and decisive pressure from the world on the terrorist state,” Mr. Zelensky added, referring to Russia.
Mr. Peskov, in warning against such a step, accused the government in Kyiv of using the zone covered by the deal “for military purposes,” without elaborating.
At a meeting in India of finance ministers of the Group of 20 nations, several of them condemned Russia’s termination of the grain deal, Nirmala Sitharaman, India’s finance minister, said in a news conference on Tuesday. The group also failed to agree on its customary joint statement because they could not agree on how to characterize the war in Ukraine. Russia and China belong to the group, which encompasses the world’s largest economies.
“We still don’t have a common language on the Russia-Ukraine war,” Ms. Sitharaman said. “It must be left to the leaders during the summit in September to take a call on that.”
The attack on the bridge illustrated the particular risk posed by drones — they can be hard to detect, carry enough fuel to travel far and do damage worth far more than the cost of making them. For Ukraine, whose navy is far outmatched by Russia’s, the appeal is readily apparent.
Unmanned vehicles can be used “against the military vessels, the cargo vessels, the logistics vessels of your adversary, and the completely lopsided costs is what’s driving this approach,” said Sam Bendett, an expert in drones and Russia’s military at C.N.A., a research institute in Virginia.
He said the vessels were probably guided by satellite, traveled slowly enough to minimize their wake and foil radar detection, and could carry hundreds of pounds of explosives.
Russia said in October that Ukraine had attacked its naval base in Crimea with marine and aerial drones, though it was unclear how much damage they did. On Sunday, Russia’s Defense Ministry said it had foiled another such attack in Sevastopol, involving two sea drones and aerial drones. There was no independent confirmation of the claim.
Marc Santora reported from Odesa, Ukraine; Ivan Nechepurenko from Tbilisi, Georgia; and Matthew Mpoke Bigg from London. Victoria Kim contributed reporting from Seoul, and Alan Rappeport from Gandhinagar, India.