Microsoft has stopped offering its Windows Live Messenger instant messaging (IM) service in five countries that are subject to sanctions by the US government. These countries are Cuba, Iran, North Korea, Sudan, and Syria.

"Microsoft has discontinued providing Instant Messenger services in certain countries subject to United States sanctions," a Microsoft statement reads. "Details of these sanctions are available from the United States Office of Foreign Assets Control."

According to that organization, the five countries in question are hostile to the United States or threaten its national interests, though the sanction details differ from country to country. The timing of the shutdown is unclear and it's not known whether the US government ordered the action. The Office of Foreign Assets Control notes that sanctions extend to "organizations physically in the United States, and all branches and subsidiaries of US organizations throughout the world."

Users in those countries that attempt to log on to the Messenger service receive an innocuous error message, "Error 810003c1: We were unable to sign you in to the .NET Messenger Service." Microsoft provided information about this error late last week on the Messenger blog.