Ukrainian anti-ship missiles, jet-powered aerial drones and sea drones blitzed a major Russian naval base on the Black Sea coast in a “unique” nighttime operation, Ukrainian President Volodymyr Zelenskyy said Wednesday.

Cutting-edge drones developed by Kyiv since Russia invaded more than four years ago have repeatedly targeted Russian ships in the Black Sea, including warships and oil tankers. Both countries have Black Sea shorelines.

Ukraine’s uncrewed fleet has succeeded in limiting the movements of Russia’s once-dominant Black Sea navy, Kyiv officials say, in one of the country’s biggest accomplishments of the war.

But Ukrainian officials reckon that Russian President Vladimir Putin is bent on prosecuting the war, despite his bigger army’s slow and costly progress on the battlefield and U.S. diplomatic efforts to find a settlement.

Putin is planning “an additional rapid mobilization of several hundred thousand Russians by the end of the year,” Zelenskyy said on social media late Tuesday, citing Ukrainian intelligence reports.

Ukraine says it hit Black Sea port infrastructure

The Ukrainian military “carried out a unique operation targeting the naval base in Novorossiysk — the last major stronghold of the Russian fleet in the Black Sea,” Zelenskyy said in a social media post Wednesday.

The attack struck air defenses, piers and other port infrastructure in the Krasnodar region city, he added.

Krasnodar region Gov. Veniamin Kondratyev said that hundreds of Ukrainian drones attacked Novorossiysk, Anapa and Gelendzhik and the Temryuk district of the region overnight.

Russian air defenses downed more than 500 Ukrainian drones, the Defense Ministry in Moscow said.

In Novorossiysk, an eight-year old child was killed in the attack, and a person wounded when his house in the Temryuk region was hit later died in hospital, Kondratyev said. He added that 12 other people in the region were wounded.

Debris from downed drones fell on the territory of four industrial plants and 21 residential buildings, according to Kondratyev, but officials gave no details of any damage.

Novorossiysk is also home to a key international oil terminal. The Grushovaya oil transshipment complex near Novorossiysk is one of the largest transshipment hubs in southern Russia for oil and petroleum products.

Last February, the U.S. State Department expressed its displeasure about Ukraine’s attacks on Novorossiysk, saying they have impacted U.S. oil interests in Kazakhstan.

The Caspian Pipeline Consortium operates a pipeline from the Caspian coast in northwest Kazakhstan to Novorossiysk. The pipeline handles much of the crude exports from three major Kazakh fields in which major U.S. energy companies, Chevron and ExxonMobil, have stakes.

In illegally annexed Crimea, air defenses downed 115 Ukrainian drones over Sevastopol overnight, the city’s Russia-appointed head Mikhail Razvozhayev said, adding that 10 apartment buildings and 25 private houses were damaged.

Russian drone attacks kill 2 and destroy a shopping mall

Meanwhile, Ukraine’s air force said Wednesday that Russia fired 138 long-range strike drones as well as an unspecified number of missiles at Ukraine during the night. Damage was recorded at 16 locations across the country, it said.

In the southern Kherson region of Ukraine, a large-scale Russian drone attack overnight killed two people and wounded two others, regional head Oleksandr Prokudin said Wednesday.

The attacks also destroyed a shopping mall in the southern Ukraine city of Zaporizhzhia, according to authorities.