Kazakhstan’s giant Karachaganak oil and gas field cut crude production by more than a quarter after a drone attack forced the shutdown of a processing plant in Russia that handles its gas.

Karachaganak, one of Kazakhstan’s three largest hydrocarbon projects alongside Tengiz and Kashagan, accounts for about 10% of the country’s oil production. Because the field produces crude oil and natural gas together, it cannot significantly reduce gas output without also curtailing oil production.