Several foreign tour operators said North Korea will begin banning foreign tourists starting Wednesday.

According to Reuters, the ban is in response to the spread of a new coronavirus outbreak in China.

The virus has killed nine people and spread to several countries including Japan, Thailand, and the United States.

The vast majority of tourists to North Korea come from China, Pyongyang’s main supporter.

Travel companies were told an order banning entry of tourists from China would be in effect until a vaccine is developed.

North Korea is estimated to earn millions of dollars from Chinese tourists each year.

South Korean budget airline T’way Air said it has postponed flights to certain areas of China due to the virus.