The US administration has issued a formal diplomatic warning to Ukraine following drone strikes on Russia’s Black Sea port of Novorossiysk that reportedly affected American economic interests tied to Kazakhstan’s oil exports.

Ukrainian Ambassador to the United States Olga Stefanishyna confirmed that Kyiv received a demarche from the US Department of State after the attacks, The Caspian Post reports via Kazakh media.

She said Washington expressed concern that Ukrainian strikes had impacted American investments operating through Kazakhstan and urged Kyiv to avoid actions that could harm US economic interests.

The warning reportedly focused on commercial stakes rather than military coordination. The November drone strikes damaged infrastructure linked to the Caspian Pipeline Consortium - a critical route for exporting Kazakh crude from major fields such as Tengiz Field, Kashagan Field, and Karachaganak Field.

US energy giant Chevron is one of the major shareholders in the consortium, which transports oil to global markets via Novorossiysk.

Stefanishyna noted that Washington’s message underscored the scale of US economic interests in Kazakhstan. Meanwhile, despite ongoing US-brokered diplomatic efforts, negotiations between Ukraine and Russia have yet to deliver a breakthrough, and hostilities continue.