Hong Kong (CNN)- It’s the nagging glitch in the US-China relationship that was inevitably mentioned during the first US presidential debate this week between Donald Trump and Hillary Clinton — cyber warfare.

During the debate, Trump questioned whether Russia was indeed behind a series of cyberattacks on the Democratic National Committee — a conclusion that US officials and his election rival have reached.
“She says, ‘Russia, Russia, Russia,'” said Trump. “It could be China.”

In the dark world of cyber-espionage, the finger of blame has often been pointed at China.
Earlier this year, China’s cyber spies were accused of hacking into dozens of workstations and servers at the Federal Deposit Insurance Corp.
Last year, Chinese hacking was blamed for the massive data breach at the US Office of Personnel Management which compromised the data of over 21 million people.
And in May 2014, US federal prosecutors indicted members of the People’s Liberation Army (PLA) for cyber-espionage for economic gain.
China has all along denied the allegations of state-sponsored hacking. But analysts say China’s cyber operations are an active threat.
“Military intelligence has rapidly moved from cloak-and-dagger to bits-and-bytes over the last fifteen years… and China’s no exception to that,” says Bryce Boland, Asia-Pacific CTO of FireEye, a cybersecurity firm.
“China has been developing its capabilities within the PLA for a number of years, going back at least a decade. And their capabilities have now also been brought together into a single, strategic organization that is essentially a new branch of the military.”