The backbone of America’s future wireless communications could be under threat, according to a congressional hearing Wednesday on the security of 5G.

Sen. Maria Cantwell (D-WA) argued that the new 5G networks could be prone to foreign interference, particularly if they relied on foreign-built hardware that could be vulnerable to supply chain attacks. “We must be certain that there is a secure supply chain backing up our 5G system,” Cantwell said. “We cannot tolerate a leaky valve or a back-door into these networks.”