WASHINGTON, United States (AFP)—The United States on Thursday announced sanctions against Cuba’s key state-owned oil company, intensifying pressure on the island nation’s energy sector that has crippled the country.

“Today, I am designating Cuba’s state-owned oil and gas company Union Cuba-Petroleo (CUPET), key assets of which were unlawfully expropriated from American owners years ago,” US Secretary of State Marco Rubio said in a statement.

The move bars companies and individuals associated with the United States from engaging in any financial transactions with CUPET, which controls extraction at Cuban crude oil fields as well as refining and distribution.