Kazakhstan lodged a formal diplomatic protest with Ukraine on Sunday following a Ukrainian naval drone attack that severely damaged a critical loading facility at the Caspian Pipeline Consortium's Black Sea terminal.
The November 29 strike on the Yuzhnaya Ozereevka terminal near Novorossiysk, Russia, rendered one single-point mooring inoperable and forced a complete suspension of oil exports.
No casualties or oil spills were reported, but operations remain suspended.
The Caspian Pipeline Consortium said one of its single-point moorings was rendered inoperable, forcing the withdrawal of tankers from the area.
The 1,500-kilometer pipeline transports crude primarily from Kazakhstan's Tengiz, Karachaganak, and Kashagan fields, accounting for roughly 80% of the country's oil exports.
Shareholders include Kazakhstan's state-owned KazMunayGas, Chevron, ExxonMobil, Lukoil, and other international firms.
Kazakhstan's foreign ministry described the incident as the third deliberate attack on an exclusively civilian facility protected under international law.
The ministry said the strike harms bilateral relations and urged Ukraine to take effective measures to prevent recurrence.
Kazakhstan's energy ministry separately condemned actions against purely civilian critical infrastructure as unacceptable.
The CPC plays a central role in ensuring uninterrupted global energy supplies, Kazakh officials stressed.
Ukraine has conducted multiple attacks this year on Russian oil infrastructure to disrupt revenue supporting Moscow's war effort.
Kyiv maintains its operations target only Russian military-related assets and are not directed at Kazakhstan or third countries.
Russia has characterized such strikes as terrorism.
The incident underscores growing risks to neutral countries' economic interests amid the ongoing conflict.