The United States is ready to impose sanctions on Turkey over its purchase of Russian S-400 air defense systems last year, four sources including two US officials told Reuters on Thursday.

China’s Foreign Ministry said Thursday it is restricting travel by some U.S. officials to Hong Kong after the U.S. placed financial sanctions and a travel ban on 14 Chinese officials.

The partnership between the US Department of Defense (DoD) and the Central Intelligence Agency (CIA) has stood for decades and often involves Pentagon officials offering a variety of support, including logistics and transportation, to the spy agency.