A former CIA officer was sentenced Friday to 19 years in prison for conspiring to provide classified information to China, marking the conclusion of a prosecution that came as the U.S. Justice Department stepped up efforts to counter what national security officials contend is an increasingly persistent Chinese campaign to obtain U.S. government and business secrets.

Jerry Chun Shing Lee, who resigned from the CIA in 2007 after more than a decade as a case officer, admitted in May that he had communicated with agents of China’s spy service between 2010 and 2018 and prepared documents in response to their requests for information. As part of his plea deal, prosecutors dropped charges related to retaining classified information.