Europe may start sanctioning Russian energy supplies soon, while it won’t be easy for the bloc to quickly reduce its imports of natural gas, according to energy historian Daniel Yergin.

“I think we’re going to start to see sanctions,” Yergin said in a Bloomberg Television interview. Pressures have mounted over the past two weeks on countries to take further action to isolate Russia as its invasion of Ukraine continues, he added. 

Yergin says it will be easier for Europe to cut down on Russian crude oil rather than natural gas. Europe relies on Moscow for about 40% of its gas consumption. Still, the bloc could be “chipping away” at Russian gas while building more terminals to receive liquefied natural gas imports.