Hackers alleged to be linked to China are accused of carrying out a second attack within a few days. The security of 4 million current and former employees of the US government has been compromised.
The data gathered could be used to gain access to secure data on other networks. Further attacks are feared.
The controversy's expected to overshadow annual bilateral talks.
Why does the US seem so vulnerable to hacking? And how will Washington respond?
Presenter: Mike Hanna
Jia Xiudong - senior research fellow at the China Institute of International Studies.
Mike Lyons - senior fellow at the Truman National Security Project.
Gavin Millard - technical director at Tenable Network Security.
Source: Al Jazeera