Russia's crude oil shipments slipped in the latest week as new US sanctions and the gradual restoration of flows from Saudi Arabia's west coast intensify competition in Moscow's key markets. In the four weeks through Sept. 20, Russia's overseas crude volumes nudged down to 3.53 million barrels a day, tanker-movements data compiled by Bloomberg showed. The weekly measure dropped by a bigger margin amid a halt of cargoes departing the Black Sea port of Novorossiysk.

Returning Saudi crude exports and the threat of US tariffs could eat into the Kremlin's war chest. The decline comes as Saudi Arabia restores output from its Red Sea facilities, adding supply to markets where Russian barrels have dominated. Meanwhile, Washington's latest sanctions package targets tankers and traders moving Russian oil above the price cap, complicating logistics for the world's second-largest exporter.

Traders are watching whether the dip marks a temporary disruption or the start of a sustained downtrend in Russian flows.