Compare and contrast…

Travel to Cuba

ENTRY / EXIT REQUIREMENTS, TRAVEL TRANSACTION LIMITATIONS: The Cuban Assets Control Regulations are enforced by the U.S. Department of the Treasury and affect all U.S. citizens and permanent residents wherever they are located, all people and organizations physically located in the United States, and all branches and subsidiaries of U.S. organizations throughout the world. The regulations require that persons subject to U.S. jurisdiction be licensed in order to engage in any travel-related transactions pursuant to travel to, from, and within Cuba. Transactions related to tourist travel are not licensable. This restriction includes tourist travel to Cuba from or through a third country such as Mexico or Canada. U.S. law enforcement authorities enforce these regulations at U.S. airports and pre-clearance facilities in third countries. Travelers who fail to comply with Department of the Treasury regulations could face civil penalties and criminal prosecution upon return to the United States.

http://travel.state.gov/travel/cis_pa_tw/cis/cis_1097.html

Travel to North Korea

SMART TRAVELER ENROLLMENT PROGRAM (STEP) / EMBASSY LOCATION: There is no U.S. embassy or consulate in North Korea. The Department of State warns U.S. citizens against entering North Korea (see Travel Warning ), without first having received explicit official permission and an entry visa from the government of North Korea.

http://travel.state.gov/travel/cis_pa_tw/cis/cis_988.html