A drone maneuvers as it approaches the vessel claimed to be a Russian large landing ship, the Olenegorsky Gonyak, close to the Black Sea port of Novorossiysk on Friday. Associated Press

KYIV, Ukraine — Ukraine said its sea drones struck a major Russian port Friday and damaged a warship in an attack that underlined Kyiv’s growing naval capabilities as the Black Sea becomes an increasingly important battleground in the war.

The strike on Novorossiysk halted maritime traffic for a few hours and marked the first time a commercial Russian port has been targeted in the nearly 18-month-old conflict. The port has a naval base, shipbuilding yards and an oil terminal, and is key for exports. It lies about 60 miles east of Crimea, where Russia’s Defense Ministry said it thwarted another attack.

The Security Service of Ukraine and the country’s navy carried out the attack that damaged the Olenegorsky Gornyak, a landing vessel of the Russian navy, according to an official with the security service. The official, who spoke on condition of anonymity because he was not authorized to give the information to the media, said the attack rendered the ship unable to perform combat missions.

Satellite photos analyzed by The Associated Press appeared to show the ship leaking oil. An image from Planet Labs, taken a few hours after the attack, showed a ship dockside with another vessel next to it. The ship in the image matched the measurements of the Olenegorsky Gornyak, as well as known physical features of the vessel. Images posted on social media showed a ship listing.

Ukrainian President Volodymyr Zelensky noted that he had received a report from the country’s security service, the SBU, but didn’t say what was in it.

“I will only say that we are all grateful to the Security Service of Ukraine for pushing back the war to the aggressor state. What you bring to the world, you end up with the same,” he said. Oblique references to attacks carried out against Russia are common for Ukrainian officials, who often do not take credit for them or only do so days after the fact.

Friday’s attack was the latest in a series of strikes inside Russia, including two in Moscow that unsettled residents. It also reflected an increase in fighting in the Black Sea following the Kremlin’s withdrawal from a deal that allowed Ukraine to export its grain through the waterway.

On Wednesday, Russian drones caused significant damage and a huge fire at grain facilities in the Odesa region. A day earlier, the Russian military said Kyiv’s forces tried to attack two of its patrol vessels at sea southwest of the Russian-controlled city of Sevastopol in Moscow-annexed Crimea.

Mykhailo Podolyak, an adviser to Zelensky, heralded the latest attack, saying it showed “drones are changing the rules of the game … and ultimately destroying the value of the Russian fleet.”

The Olenegorsky Gornyak warship stands moored at the harbor of Novorossiysk, Russia, on July 30. Russia accused Ukraine early on Friday of attacking its Black Sea navy base in the port of Novorossiysk with sea drones. Associated Press Photo

Russia’s far superior navy has controlled the seas in the war so far. Its ships have regularly launched cruise missiles at major ports and cities across Ukraine, and they have largely blockaded the country’s coast as well as mined the Black Sea, making passage through it treacherous.

Podolyak’s remarks and other recent attacks in the sea and on the Kerch Bridge connecting Crimea to Russia could indicate Ukraine is trying to change that dynamic.

With the latest assault, “Kyiv showed that it can attack any vessel of the Black Sea Fleet, no matter the distance,” said Ukrainian military analyst Roman Svytan.

The end of the grain deal, under which ships carrying food from Ukrainian ports were promised safe passage, “untied Kyiv’s hands,” he said, predicting the frequency of attacks on Russian ships would only increase.

While Friday’s attack served as an important morale booster for Ukraine, challenging Russia’s naval power in the Black Sea will be hard for Ukraine.

The Russian Black Sea Fleet has nearly 50 warships, seven submarines and many support vessels, dwarfing the capability of Ukraine, which said it lost more than 80% of its naval capabilities after Moscow’s illegal annexation of Crimea.

Despite Russia’s superiority, Ukrainian missiles last year sank the fleet’s flagship, the Moskva missile cruiser, and destroyed the Saratov landing ship in the occupied port of Berdyansk. Several more vessels have reportedly been damaged.

The Russian Defense Ministry claimed that the navy fended off Friday’s attack, saying that its ships destroyed two Ukrainian sea drones. Footage published on Russian social media channels appeared to show a ship firing into the sea and a burning object exploding.

But other images that appeared on messaging app channels claimed to show the Olenegorsky Gornyak listing to one side, and some Russian military bloggers confirmed that it was damaged. Ukrainian media outlets also carried footage they said was from a drone’s onboard camera showing it approaching the Russian landing ship.

The AP could not verify the videos.

Kremlin spokesman Dmitry Peskov refused to comment on the attack during a conference call with reporters.

The Caspian Pipeline Consortium, which operates an oil terminal in Novorossiysk, said maritime traffic was halted for a few hours but that its facilities were not damaged. The regional governor said there were no casualties.

Minutes after confirming the attack on the Black Sea port early Friday, Russia’s Ministry of Defense said it had also repelled another attack by Ukraine on Crimea. The ministry said air defense systems shot down 10 drones and jammed another three.

Videos shared on Russian social media channels reportedly from around the city of Feodosia showed what appeared to be air defense systems working, as well as loud explosions.

Last month, another Ukrainian attack struck a key bridge that links Russia to the peninsula it illegally annexed in 2014 and serves as a key artery for sending military and civilian supplies to Crimea and sustaining Russia’s war effort.

In other developments:

• The U.N. atomic watchdog said its monitors at the Russian-occupied Zaporizhzhia Nuclear Power Plant have observed no mines or explosives on rooftops of reactor units 3 and 4 and or the plant’s turbine halls after having been given access the previous day. Ukraine’s military intelligence said in June, without providing evidence, that Russia had placed suspected explosives on the roof and was planning a “large-scale provocation.”

The International Atomic Energy Agency cited its chief, Rafael Mariano Grossi, saying that the monitoring team “continues to request to visit the roofs of the other 4 units.” The IAEA has repeatedly expressed concern about a potential radiation leak from the plant. Its six reactors have been shut down for months.

• Saudi Arabia said it will host an international meeting on the Ukraine war on Saturday to be attended by national security advisers and other officials. The talks will be held behind closed doors, like the first such meeting in Copenhagen in June. Officials have said Ukraine will be represented, while Russia was not invited.

Saudi Arabia’s assertive Crown Prince Mohammed bin Salman has sought to position himself as a possible negotiator in the war. The kingdom hosted an Arab League summit earlier this year that President Volodymyr Zelensky attended. The kingdom maintains close ties to Russia through OPEC+.

• The Moscow-appointed governor of the Russia-occupied part of the Zaporizhzhia region, Yevgeny Balitsky, said several Ukrainian drones were shot down near the Sea of Azov port city of Berdyansk during the night.

Burrows reported from Tallinn, Estonia. Associated Press writers Jon Gambrell in Dubai, United Arab Emirates, and Geir Moulson and Yuras Karmanau in Berlin contributed to this report.