Afghanistan is one of two countries in which the spread of the potentially fatal, paralyzing disease has never been stopped. No reason was given for the suspension.

The Taliban have suspended polio vaccination campaigns in Afghanistan, the U.N. said Monday. It’s a devastating setback for polio eradication, since the virus is one of the world’s most infectious and any unvaccinated groups of children where the virus is spreading could undo years of progress.

The Taliban has suspended polio vaccination campaigns across Afghanistan, the United Nations announced Monday. News of the suspension was relayed to U.N. agencies right before the September immunization campaign was due to start.