By this measure, an opposite of a liberalized economy are economies such as North Korea's economy with their "self-sufficient" economic system that is closed to foreign trade and investment (see autarky). However, North Korea is not completely separate from the global economy, since it actively trades with China, through Dandong, a large border port and receives aid from other countries in exchange for peace and restrictions in their nuclear programme. Another example would be oil-rich countries such as Saudi Arabia and the United Arab Emirates, which see no need to further open up their economies to foreign capital and investments since their oil reserves already provide them with huge export earnings.