At the lows today, WTI crude oil was down to $89.05 but was holding around $90.00 before the headlines crossed. It is now trading up to $91.70 as Reuters is reporting that Russia has suspended oil exports via the southern leg of the Druzhba pipeline amid transit payment issues.
It is said that the payment from Russia's pipeline monopoly, Transneft, to Ukraine's pipeline operator, Ukrtransnafta, did not go through. For some context, the flows here i.e. southern part of the Druzhba pipeline, goes towards Hungary, Czech Republic, and Slovakia.
Update: Transneft has come out to say that the northern part of the pipeline, in which flows goes towards Germany, is unaffected.