U.S. tech companies would be forced to disclose if they allowed American adversaries, like Russia and China, to examine the inner workings of software sold to the U.S. military under proposed legislation, Senate staff told Reuters on Thursday.

The bill, approved by the Senate Armed Services Committee on Thursday, comes after a year-long Reuters investigation reut.rs/2kgSpjW found software makers allowed a Russian defense agency to hunt for vulnerabilities in software that was already deeply embedded in some of the most sensitive parts of the U.S. government, including the Pentagon, the Federal Bureau of Investigation and intelligence agencies.

Security experts say allowing Russian authorities to conduct the reviews of internal software instructions — known as source code — could help Russia find vulnerabilities and more easily attack key systems that protect the United States.