Moscow warned that it is unsafe to navigate in its Black Sea waters after Ukraine has been ramping up attacks on Russia-linked ships in the area.

The warning was addressed to all vessels in Russia’s exclusive economic zone in the Black Sea and cites potential threats from Ukraine’s unmanned aerial and marine vehicles, according to a weekly bulletin published on the website of the country’s Defense Ministry on July 22.

The exclusive economic zone is a maritime area stretching up to 200 nautical miles from the coast. Russia’s EEZ in the Black Sea allows access to several national ports including Novorossiysk, a key regional outlet for commodity exports.

The Defense Ministry’s notice comes as Ukraine has been making multiple daily attacks on vessels in the Black Sea and the Sea of Azov in a move to choke off Russia’s commodity export flows, and bring the Kremlin to the negotiating table. Any prolonged interruptions in oil exports across the Black Sea could add further pressure to global markets as the U.S.-Iran war disrupts shipments from the Strait of Hormuz and the Red Sea.

At least 124 Russia-linked vessels were targeted in the Black Sea and the Sea of Azov, including 89 tankers, from July 8 to July 20, according to statements from Ukraine’s General Staff. Bloomberg couldn’t independently verify the number of attacked vessels. 

Following the strikes, the port of Novorossiysk issued a temporary verbal ban on navigation between midnight and 5 a.m. local time for security reasons. The restrictions alone could affect at least some loadings at the port, which normally happen round the clock. 

Russia has also been attacking Ukraine’s key Black Sea ports, including Odessa and Chornomorsk. As a result, shipowners have temporarily suspended vessel arrivals at Ukraine’s Black Sea ports for agricultural exports, Interfax-Ukraine reported earlier on July 23, citing agriculture minister Taras Vysotskyi. 

The Caspian Pipeline Consortium earlier this week was forced to stop crude loadings from its Black Sea terminal in response to the security concerns of shipowners. The CPC is the single largest outlet for Kazakhstan’s crude, accounting for around 80% of export flows. As a result of the halt, the Central Asian nation has been forced to cut oil production.