The USA Patriot Act requires all US businesses be OFAC Compliant. This includes checking OFAC and SDN lists as well as FBI terrorist and interpol plus many other databases for countries, individuals, and groups known to be terrorists and narcotics traffickers.
Instant OFAC Search
OFAC is the Office of Foreign Asset Control which is the financial enforcement agency of the US Treasury that enforces economic compliance.
Businesses working with overseas partners can unwittingly do business with terrorist organizations or other unsanctioned terrorist entities.
Use this OFAC Search to stay compliant.