Russia can no longer send gas to Europe using Ukraine's pipelines, a network it's used to earn billions even while at war with Kyiv.Contributor/Getty Images and Pier Marco Tacca/Getty ImagesEven while at war, Ukraine has been piping gas for Russia to European customers.But that arrangement, which dates back to the fall of the Soviet Union, has now expired.Russia was estimated to rake in $5 billion in 2024 from the gas transits, with Ukraine getting up to $1 billion.Russia is no longer able to send natural gas to Europe through Ukraine's pipelines after a five-year deal, struck before the war began, expired on Wednesday.It marks the end of a long-standing arrangement that used Ukraine as a conduit for westbound Russian gas — an agreement that continued even as full-scale war broke out in 2022.European countries that received that gas, such as Slovakia and Austria, were paying Russia for this energy.