Data just released by the national Computer Emergency Response Coordination Team shows China is one of the primary targets of cyber attacks and US-based hackers are most responsible for attacks on Chinese computer networks.

The country’s top cyber security agency says nearly 11 million computers on Chinese mainland were infected and controlled by overseas servers in 2013 and US hackers accounted for over 30 percent of the attacks. More than 61,000 Chinese websites were infected by backdoor intrusions from foreign hackers in 2013, that’s an increase of 62 percent compared to the year before.

Backdoor malware, phishing scams and botnets were the main tools used by foreign hackers to invade PCs in China.