A domestic airport is an airport that handles only domestic flights—flights within the same country. Domestic airports do not have customs and immigration facilities and so cannot handle flights to or from a foreign airport. These airports normally have short runways sufficient to handle short or medium haul aircraft and regional air traffic. They have in many countries not had any security check / metal detector, but such checks have been added in recent years. Most municipal airports in Canada and the United States are of this classification. At international airports in Canada, there are domestic terminals that handle flights within Canada (flying from one Canadian city to another). In the United Kingdom, an example of a domestic airport is Plymouth City Airport, which formerly operated frequent flights to other UK airports. Despite being the smallest UK airport, it was the main hub for Air Southwest until the airline pulled out of the airport in July 2011 as part of the airline’s closure due in September 2011. Some small countries or regions do not have any public domestic airports, or even public domestic flights, due to its size, e.g. Belgium, Hong Kong, Macau, Singapore, and the United Arab Emirates.