Your card is useless in these countries - bulletproof vest is a must have in some

It was a good news this spring about easing the financial sanctions imposed by the US on Cuba. US business quickly followed a new guidance from the US Treasury’s Office of Foreign Assets Control, finding new business opportunities and fixing lost ties to the island.

MasterCard was among the first ones to start accepting merchant payments from Cuba on US issued credit cards. Starting March 2015 US customers are able to pay for services in Cuba using American credit cards. Another problem is the merchant infrastructure that is missing for the majority of the small businesses, but probably if American tourists will flood the island, merchant will follow quickly.

Lets see what other countries still have a ban from US government on financial transactions with US counterparts (meaning, you will not be able to use a US issued credit card there).

Those countries have been under US ‘comprehensive sanctions’ for sponsorship of terrorism. The list is short now with only Sudan, Iran, and Syria. The list is changing - in 2011 Syria was included and in 2012 Myanmar (Burma) managed to get off the list.

I hope that in some near future Iran sanctions will be lifted as well and one more country will start accepting US credit cards. 

Russia-Ukraine situation also resulted in partial sanctions that forced VISA and MasterCard to seize operations in the disputed territory of Crimea peninsula. Just recently both payment systems announced a partnership with a new Russian National Payment Card System and plans to resume operations on the peninsula in April 2015.

See the full list of US sanctioned countries here