Senate investigators confirmed Wednesday that Chinese government-linked hackers infiltrated digital networks of private companies working for the U.S. military. The online break-ins occurred 20 times in one year, however the U.S. Transportation Command was only told about two of these incidents.

The Transportation Command, which is in charge of moving troops and supplies around the world, was examined by the Senate Armed Services Committee, who said the low reporting may have been due to the fact that the command was unaware of the probing.

The contractors used by Transportation Command include passenger and cargo airlines and ship operators and the communications between the government and these partners are what was vulnerable to surveillance.

The Senate's committee oversaw these companies from June 2012 to June 2013 and said that these breaches are not reported to subcontractors or other related businesses, so the problem is not contained. While these messages may seem trivial, the operations of these companies could prove lethal in enemy hands.

The roundabout spying technique avoids the heavily-guarded Defense Department, making it easier to gather second-hand information about military activity and strategy.

"The security of our military operations are what is at stake," chairman of the Armed Services Committee, Sen. Carl Levin, said in a recent news conference. "What we found was very disturbing."

Chinese officials responded that the report was not factual.

"Making groundless accusations at others is not constructive at all and does not contribute to the solution of the issue," a spokesperson from the Chinese embassy in Washington said.

The connection of the cyberattacks to China were made by the executive branch, according to Senate aides. They did not give specific evidence for support.

Transportation Command was not available for comment.