Cuba and Iran are only isolated from the US, and the US was never a major part of their foreign trade. North Korea only survives because it is propped up by external powers (China, and to a lesser extend, South Korea).<p>In contrast, China makes many consumer electronics intended for the US market.<p>International isolation worked fairly well for South Africa. Threads of isolation also opened up the Japanese and Chinese markets to US-made auto parts, and it opened the domestic Chinese consumer electronics market to foreign-made semiconductors.