On October 31, senior State Department official Thomas Zarzecki landed in Belgrade to meet Serbian officials over the announced purchase of sophisticated anti-aircraft missile systems from Russia.

“CAATSA is very serious about this”, a senior Western diplomat told New Europe just before Zarzecki landed in Serbia’s capital.

Zarzecki heads the “Task Force 231”, which oversees the implementation of Section 231 of the Countering America’s Adversaries Through Sanctions Act of 2017 (CAATSA), by developing and implementing sanctions and policy initiatives against those engaged in significant transactions with Russia’s defence and intelligence sectors.

https://www.neweurope.eu/article/us-queries-serbia-about-russian-arms-purchases-amid-eu-nato-turmoil/