Following a terrorist attempt in October 2010 involving explosives concealed in U.S.-bound packages from Yemen, U.S. Customs and Border Protection (CBP) and the Transportation Security Administration (TSA) worked to enhance air cargo supply chain security by piloting ACAS to target shipments inbound to the United States. CBP’s legal authority is derived from the Trade Act of 2002; TSA’s legal authority comes from the Aviation Transportation Security Act.