The Hmong are an ancient culture located predominantly in the mountains of Northwest Vietnam, Northeast Laos and areas of China bordering Vietnam and Laos. The Hmong are arguably the most closely related of over fifty cultures in Vietnam to the Kinh (a.k.a. Vietnamese).
The Hmong were secretly recruited by the U.S. through the CIA to disrupt the NVA along the Ho Chi Minh Trail and to infiltrate into North Vietnam. They were recruited, trained and supplied in Laos. They were effective by being able to slip through the rugged mountains in that area at will because it was their homeland.
The Hmong didn't replace "white boys", because there were no "white boys" to replace in that region of the War. U.S. soldiers never officially infiltrated North Vietnam (however, there are several unofficial accounts), but the Hmong were able to because their homeland expanded into Vietnam and China. $2/month for the Hmong was a lot of money for them back then, and many volunteered to fight because they hated the communist.
After the U.S. pulled out of Southeast Asia, Hmong tribes in Laos started to fight among themselves and with the Laos government when the country turned to communism. This is a civil war that is still continuing to some extent today and has caused the Hmong homeland to be a very dangerous and deadly place to live.
The U.S. had made Hmong immigration easier under political asylum due to hostilities in their homeland. Many of them settled in the Upper Midwest, because that region's climate is comparable to their homeland. The Hmong are a very hard working and extremely resourceful, which has resulted in them adapting and becoming very successful in a short time.
The "leader" that was arrested was trying to send guns, bombs and military equipment to a Hmong tribal resistant forces in Laos. Plainly speaking - you don't go around shipping tons of military equipment from the U.S. to a foreign country without getting into a lot of trouble if you get caught. So don't blame Bush for that.
U.S. interests in Laos may have fueled the conflicts in Laos, but the U.S. is not the one who caused them to fight or continue to fight for decades. This is a classic civil war among The Hmong and Laotians that has more to do with controlling opium agriculture than a fight against communism. The weapons provided by the U.S. to the Hmong are well over 30 years old. The bullets provided for those guns were expended decades ago, which means someone else has been providing the bullets.