HOLLAND
Japan
north Korea
There are a number of Asian countries that use nuclear power, Japan, China, India, Pakistan, and others.
Thailand is the only country in Southeast Asia that was never colonized by a European power. It maintained its independence by skillfully negotiating with colonial powers and playing them off against each other.
europe
North Korea
Holland
There are several Asian countries that could be considered secretive and who use nuclear power. For instance, there are North Korea and China.
In the World War II era, the "Greater East Asia Co-Prosperity Sphere" was established by Japan with the stated intent to unite Asian peoples against Western dominance while also bringing great economic gain to each of the nations joining it. Its general "meaning," then, was to increase resistance to Western nations occupying Asian lands and/or dominating Asian resources and trade -- and to replace Western power with Japanese power allied with that of other indigenous Asian peoples.
Your question probably refers to either North Korea or Iran. There are a couple links below.
No. It was never a member of the British Commonwealth or Commonwealth of Nations. While the British did at one point control small parts of what is now modern-day Thailand's territory, the Thai monarchy remained in power and Thailand is the only Southeast Asian nation that has never been colonized by Western powers.