“Your statements come at a time when we would hope to see Americans standing up and speaking out," the legislators wrote in a letter.
Lee Meng-chu went missing after sharing photos documenting the Chinese military buildup on the Hong Kong border.
The central government in Beijing ominously characterized the current protest movement as something approaching "terrorism."
Demonstrations began early last month in opposition to an extradition bill that has since been suspended, but the movement has become a push for full democracy.
Demonstrators took to the streets again on Sunday, chanting "Free Hong Kong" and demanding the resignation of the city's leader.
Protesters oppose the government-backed legislation that would allow people to be extradited to mainland China to face charges.
The plane was carrying out a routine mission over the South China Sea, according to an Air Force official.
More importantly, what took centuries and a Great Wall to build ages ago might be accomplished almost overnight in the information
The three state-owned companies had not raised complaints because they knew the decision had been endorsed by Chinese leadership