Karen is regarded as a minority ethnic group by the Burmese government. After Burma gained independence from Britain, many ethnic groups demanded independence from the central government but their demand was turned down. Therefore, many of them formed into groups demanding self-rule from the regime, like the Karen National Union (KNU) headquartered along the western border of Thailand. Fighting between the Burmese army and the KNU has some ramifications for Thailand. In terms of security, mortar rounds cross over to the Thai side and destroy Thai villages. Burmese soldiers follow the KNU army on Thai soil. Economically, the Toleku government has natural resources that Thai merchants and the state sector need. Establishing a relationship with the Karen State is important to trade. Regarding the humanitarian issue, wounded Karen soldiers and civilians flee into Thailand and the government has to assist and shelter them. The Burmese government views this action as support for the KNU, which is a buffer state, and uses the issue as a condition for trade and investment negotiations, adversely affecting economic cooperation and relations between the two countries. As a consequence, Karen-Burmese-Thai relations are fragile with the Karen State as a significant variable in the relationship between Thailand and Burma from the past until the present.