In my opinion, China is the biggest potential threat to the United States.
China is "run" by the People's Republic of China, a combination of socialism and Communism. The "real" people of China have no input into the governing of China.
As a substitute teacher in a large metropolitan school district, I have come in contact with teachers who are promoting Chinese exchange students, who sponsor trips to China for their school students, and who have Chinese students living in their homes. There is even a Chinese-sponsored school in my city. All teacers in this school are Chinese citizens, given permission from the U.S. State Department to teach Chinese in the United States schools.
As a citizen of the United States, I do not understand why my government is allowing citizens of China to teach in the United States. I don't understand why any teacher would condone the Chinese government.