Although Tsien was one of the founders of NASA's Jet Propulsion Laboratory (JPL), and for many years helped the military of the United States debrief scientists from Nazi Germany, he was suddenly accused of being a spy and a member of the Communist Party USA, and was placed under house arrest from 1950 to 1955.
Meskipun Tsien adalah salah seorang pendiri Jet Propulsion Laboratory (JPL) milik NASA, dan menolong militer Amerika Serikat dalam melakukan debriefing terhadap para ilmuwan dari Jerman Nazi selama bertahun-tahun, ia tiba-tiba dikenai tuduhan palsu sebagai mata-mata, anggota Partai Komunis AS, dan dikenai tahanan rumah dari 1950 hingga 1955.