...due, your sources are off -- it was not DR. YANG DAO, it was DR. PAO ZE who declared it in Washington DC.
i read somewhere long time ago that it was dr. yaj dao who told the white men in the earlier years to refer us as Hmong. he also wanted the hmong chinese to call themselves hmong and not miao. reading the wikipedia about the hmong, it was dr. pao ze who probably in the 90s (not sure) wanted the word "mong" to be recognize as a different group of hmong. so if the white men is talking about a green mong, he'll have to use the term mong, and if he's talking about the white hmong, he'll have to use the term hmong. which will be even more confusing to many white men.
http://en.wikipedia.org/wiki/Hmong_people
Hmong and Mong
When Western authors came in contact with Hmong and Mong people, beginning in the eighteenth-century, they referred to them in writing by ethnonyms assigned by the Chinese (i.e. Miao, or variants). This practice continued into the twentieth century. Even ethnographers studying the Hmong/Mong people in Southeast Asia often referred to them as Meo, a corruption of Miao applied by Thai and Lao people to the Hmong/Mong. Although "Meo" was an official term, it was often used as an insult against Hmong/Mong people and it is considered to be highly derogatory.[6] In the middle of the twentieth century, a concerted effort was made to refer to Hmong/Mong by their own ethnonyms in scholarly literature. By the 1970s, it became standard to refer to the entire ethnic group as "Hmong." This was reinforced during the influx of Hmong/Mong immigrants to the United States after 1975. Research proliferated, much of it being directed toward the American Hmong Der community. Several states with Hmong/Mong populations issued official translations only in the Hmong Der dialect. At the same time, more Mong Leng people voiced concerns that the supposed inclusive term "Hmong" only served to exclude them from the national discourse.
The issue came to a head during the passage of California State Assembly Bill (AB) 78, in the 2003–2004 season.[7] Introduced by Doua Vu and Assembly Member Sarah Reyes, District 31 (Fresno), the bill encouraged changes in secondary education curriculum to include information about the Secret War and the role of Hmong/Mong people in the war. Furthermore, the bill called for the use of oral histories and first hand accounts from Hmong/Mong people who had participated in the war and who were caught up in the aftermath. Originally, the language of the bill mentioned only "Hmong" people, intending to include the entire community. A number of Mong Leng activists, led by Dr. Paoze Thao (Professor of Linguistics and Education at California State University, Monterey Bay), drew attention to the problems associated with omitting "Mong" from the language of the bill. They noted that despite nearly equal numbers of Hmong Der and Mong Leng in the United States, resources are disproportionately directed toward the Hmong Der community. This includes not only scholarly research, but also the translation of materials, potentially including curriculum proposed by the bill.[8] Despite these arguments, "Mong" was not added to the bill. In the version that passed the assembly, "Hmong" was replaced by "Southeast Asians", a more broadly inclusive term.
Dr. Paoze Thao and others feel strongly that "Hmong" can refer only to Hmong Der people and does not include Mong Leng people. He feels that the usage of "Hmong" in reference to both groups perpetuates the marginalization of Mong Leng language and culture. Thus, he advocates the usage of both "Hmong" and "Mong" when referring to the entire ethnic group.[9] Other scholars, including anthropologist Dr. Gary Yia Lee (a Hmong Der person), suggest that "Hmong" has been used for the past 30 years to refer to the entire community and that the inclusion of Mong Leng people is understood.[10] Some argue that such distinctions create unnecessary divisions within the global community and will only confuse non-Hmong/Mong people trying to learn more about Hmong/Mong history and culture.[11]