The Chinese government and military are behind large numbers of cyberattacks directed at U.S. government computer systems, according to a Pentagon report released this week.

The 83-page report, Military and Security Developments Involving the People’s Republic of China, said, “In 2012, numerous computer systems around the world, including those owned by the US government, continued to be targeted for intrusions, some of which appear to be attributable directly to the Chinese government and military.”

It is among the strongly worded statements yet in a war of words between America and China over cyberespionage - particularly the assertion that intrusions are "directly attributable" to the Chinese military. Last month U.S. Secretary of State John Kerry said during a visit to Beijing that the countries needed to “work together” on cybersecurity.

“China continues to leverage foreign investments, commercial joint ventures, academic exchanges, the experience of repatriated Chinese students and researchers, and state-sponsored industrial and technical espionage to increase the level of technologies and expertise available to support military research, development, and acquisition,” the report said.

Senior Colonel Wang Xinjun, a researcher for the People’s Liberation Army, said that the report was “"irresponsible and harmful to the mutual trust between the sides,” the official Xinhua News Agency reported. "The Chinese government and armed forces have never sanctioned hacking activities,” Colonel Wang said.