What is ‘The Shield of the Americas’ that Kristi Noem will serve as envoy to?

US President Donald Trump removed Kristi Noem as Secretary of Homeland Security and appointed her Special Envoy for 'The Shield of the Americas'. The initiative is a new US security plan aimed at improving safety and cooperation among countries in Western Hemisphere. It seeks stronger coordination among North and South American nations on border security, crime prevention and regional safety.