Russia Rejoins Grain Deal, but Warns It Could Pull Out Again

Russia on Wednesday rejoined an agreement allowing the shipment of Ukrainian grain through the Black Sea, one of the few areas of cooperation amid the war in Ukraine, easing uncertainty over the fate of a deal seen as crucial to preventing famine in other parts of the world.

Moscow had suspended its participation in the deal over the weekend after an attack on Russian warships in the Black Sea port of Sevastopol that it blamed on Ukraine — though the attack was far from the corridor used by grain ships. It was unclear why the Kremlin reversed course so quickly, but President Vladimir V. Putin said in televised remarks that the agreement was tied to Ukraine’s ensuring the safety of Russian vessels.

“Russia retains the right to leave these agreements if these guarantees from Ukraine are violated,” he said.

But Ukrainian officials suggested that Russia had reconsidered after seeing that other parties, including Turkey and the United Nations, were committed to continuing with or without Moscow’s involvement.

Tatiana Stanovaya, an analyst of Kremlin politics, said that in trying to suspend the agreement, Moscow had not counted on the other parties continuing without it.

“The Kremlin itself fell into a trap from which it did not know how to get out,” she wrote on the Telegram social messaging app.

With Russia’s navy in control of the Black Sea and effectively blockading Ukraine, one of the world’s major food exporters, Kyiv was unable to ship grain for the first months of the war. Critical global food shortages worsened, particularly in the drought-stricken Horn of Africa, and prices on world markets soared.

But the deal struck in July has allowed ships carrying more than 10 million tons of farm products to sail without incident from Ukrainian ports to Istanbul, where they have been inspected by international teams that include Russian representatives, before proceeding to their ultimate destinations.

The news that Russia would rejoin the grain deal appeared to be a bright spot for Ukraine, whose civilian infrastructure has been under relentless Russian bombardment as Ukraine prepares for a winter without enough power, heat, water or shelter — and even for the possibility of attack with a nuclear weapon or radiological “dirty bomb.”

The top official in the region of Kyiv, the capital, said officials were preparing 425 fallout shelters equipped with emergency supplies, giving radiation protective gear and training to emergency workers, and designating evacuation routes.

The New York Times reported on Wednesday that top Russian military leaders recently had conversations to discuss when and how Moscow might use a tactical nuclear weapon in Ukraine, according to senior American officials, though they have detected no signs of preparation for using one. In the past two months, as Russian forces have lost ground, Mr. Putin and other top officials have said repeatedly that Moscow could use any weapon at its disposal.

Russia’s defense minister, Sergei K. Shoigu, on Wednesday repeated the Kremlin’s claim, without offering any evidence, that Ukraine was preparing a dirty bomb, which Ukrainian and Western officials have dismissed as false and a possible pretext for Russia to do something similar.

Russia’s Foreign Ministry also accused the West on Wednesday of “encouraging provocations with weapons of mass destruction.”

In Kyiv, rolling blackouts have become a daily hardship, and Russian strikes on Monday knocked out pumping stations, leaving most of the city without running water for hours. On Wednesday, Mayor Vitali Klitschko said the city had set up 1,000 heating stations stocked with generators for residents to warm up, drink tea and charge their phones.

President Volodymyr Zelensky of Ukraine pleaded for European Union assistance, saying in a statement on Tuesday that about 40 percent of the country’s power grid was “seriously damaged.” More than 800,000 homes across Ukraine have been damaged or destroyed since the war began in February, with so many windows shattered by explosions that glass is scarce.

Russia has also significantly reduced gas deliveries to Moldova, driving up prices and creating power shortages in the country, an official in Moldova’s pro-Western government said Tuesday.

As a Ukrainian counteroffensive has retaken some of the territory Russia seized after invading, Moscow’s forces have responded with more long-range attacks on Ukraine’s power grid, heating plants and other civilian infrastructure.

But analysts say Russia is running short of some kinds of munitions. Unable to buy from most other countries, it is turning to states shunned by much of the world. Russia has bought explosive drones from Iran and used them extensively in Ukraine, and on Wednesday the White House said Russia was obtaining artillery shells from North Korea.

“Our indications are the D.P.R.K. is covertly supplying, and we’re going to monitor to see whether shipments are received,” John F. Kirby, spokesman for the National Security Council, told reporters on Wednesday, referring to the Democratic People’s Republic of Korea. “Our information indicates that they’re trying to obscure the method of supply by funneling them through other countries in the Middle East and North Africa.”

“We don’t believe that this will change the course of the war,” Mr. Kirby added.

U.S. officials have voiced concern that Russia could also be trying to get missiles from Iran and rockets from North Korea.

The grain deal has been seen by much of the world as an important achievement, but even before the Sevastopol attack, Moscow was dissatisfied with the arrangement, set to expire this month. Russia had signaled it would demand international concessions in exchange for renewal.

Though Ukrainian shipments resumed over the summer, Russia’s own crop and fertilizer exports have continued to lag far behind prewar levels, as many shipping companies, insurers and governments have been reluctant to deal with Moscow. Some fear running afoul of Western sanctions.

Russia’s threats to block the grain deal reminded the world of those concerns and of its ability to act on those concerns. The Russian Defense Ministry said on Wednesday that Moscow had agreed to rejoin the deal after receiving written guarantees from Ukraine that the waters and ports used by grain ships would not be used “for military operations against the Russian Federation” — though there has been no indication of such use.

At least 15 grain ships have departed from Ukraine since Moscow announced it was pulling out of the agreement on Saturday. But it left the Kremlin with the apparent choices of letting the program proceed without taking part, resuming participation or blocking — even sinking — badly needed food shipments to some of the world’s poorest regions.

“A ‘blackmailer’ with Russian roots is inferior to those who are stronger and know how to clearly state their position,” Mykhailo Podolyak, an adviser to Ukraine’s president, tweeted after Russia rejoined.