Huyen, who has reached the Olympic standards, will be sent to Russia for at least three months, starting in early January.
Huyen competes in the women's 400m and 400m hurdles events. She won at the recent Southeast Asian Games, but did not compete at the national championships last month because of a thigh injury.
Long jump athlete Thao is happy about her training session in the United States.
"My personal best is 6.65m, while the Olympic standard is 6.70m. I am pleased to get this opportunity to train in America to improve my result," the SEA Games silver medallist said.
"I will compete in an Asian indoor tournament next February, and hope to qualify for the Olympics in Brazil," she said.
Huyen and Thao are among the athletes who are expected to represent Vietnam at the next summer Olympics. The others are Quach Thi Lan (women's 400m), Quach Cong Lich (men's 400m), Le Trong Hinh (men's 200m) and Nguyen Thi Thanh Phuc (women's walk).