Russia has lost at least 40% of its oil export capacity after Ukrainian drone attacks, a disputed attack on a major oil pipeline and the seizure of tankers, according to a Reuters calculation.
It is the most serious oil supply disruption in the modern history of Russia - the world's second-largest oil exporter - and has hit Moscow just as oil prices have surpassed $100 a barrel due to the war with Iran.
Oil production is one of the main sources of revenue for Russia's national budget and is central to its $2.6 trillion economy dollars.
This month, Ukraine intensified its drone attacks on Russian oil and fuel export infrastructure, hitting all three of Russia's main western oil export ports - Novorossiysk on the Black Sea and Primorsk and Ust-Luga on the Baltic Sea.
About 40% of Russia's crude oil export capacity - or about 2 million barrels per day - has been shut down to date since the latest attack.
This includes Primorsk and Ust-Luga, as well as the "Druzhba" oil pipeline that runs through Ukraine to Hungary and Slovakia.
Kiev is also targeting pumping stations and refineries on the pipeline. Ukraine claims that the aim is to reduce Moscow's oil and gas revenues, which make up about a quarter of the Russian state budget, and to weaken its military power.
Russia, on the other hand, claims that the Ukrainian strikes are terrorist attacks and has tightened security measures in its 11 time zones.
Ukraine has indicated that part of the "Druzhba" oil pipeline was damaged by Russian strikes in late January, and Slovakia and Hungary have demanded that Kiev immediately resume supplies.
The Novorossiysk oil terminal, which can handle up to 700,000 barrels per day, is moving oil below schedule after damage caused by a heavy Ukrainian drone attack earlier this month.
Furthermore, frequent seizures of Russian-linked tankers in Europe have disrupted exports of 300,000 barrels per day of Arctic oil coming from the port of Murmansk.
With export routes to the west under scrutiny, Moscow must rely on oil exports to Asian markets. However, these routes are limited due to capacity, traders said.
Russia continues to supply oil to China via pipelines, including the Skovorodino-Mohe and Atasu-Alashanku routes, as well as exports of ESPO Blend by sea through the port of Kozmino. Together, the three routes account for about 1.9 million barrels of oil per day.
Russia also continues to transport oil from its two Sakhalin projects in the Far East, transporting about 250,000 barrels of oil per day from the island.
Traders said Russia also supplies refineries in neighboring Belarus with about 300,000 barrels of oil per day.