TOKYO -- The U.S. government is increasingly fearful of Chinese carrying out cyberattacks and building "backdoors" into telecommunications gear to steal military secrets. Its fears are likely justified, as China learned its spy techniques from the best in the business -- the Americans themselves.

Cases of alleged espionage by Chinese are abundant. On Dec. 20, the U.S. indicted two Chinese nationals for carrying out cyberattacks. The Department of Justice said the men stole intellectual property and confidential business information from more than 45 technology companies and government entities in the U.S., including the Navy and the NASA space agency.

Espionage has a long history. "The Art of War," the ancient Chinese military treatise, says that employing skillful espionage is more effective than unleashing many troops, and goes on to describe various types of human intelligence, or "humint" -- the use of secret agents -- to learn the enemy's movements. History books are filled with examples of how spies have plied their trade behind the scenes through the ages.

In modern times, however, humint has largely been replaced by spy schemes using hardware or software.

In the early 1980s, during the Cold War, the U.S. discovered that the Soviet Union was secretly sounding out Western sources to acquire software for controlling pipelines. The CIA, which not only gathers information from around the world but also engages in lethal covert activities in enemy states, provided the Soviets software that had been programmed to make pipelines go haywire. Unaware that the U.S. was behind the transaction, the Soviet Union installed the software in a pipeline system in Siberia.

In the summer of 1982, the pipeline became uncontrollable and exploded as planned. It was said to have been the biggest non-nuclear man-made explosion ever.

The installation of spying functions in hardware and software has grown along with the global spread of computers.

Stuxnet, a malicious computer worm that emerged in 2010, is alleged to have been developed jointly by the U.S. National Security Agency and Israel's intelligence agency. It is known to have temporarily shut down uranium-enrichment facilities in Iran, which has an antagonistic relationship with both countries.

The U.S. is a pioneer when it comes to rigging hardware and software to spy on enemies. China, which has been honing the art of espionage since ancient times, has merely taken a page from the U.S. playbook and is enthusiastically putting its new skills into practice.

This reality needs to be taken into account when considering the U.S.-China relationship and the friction between the countries. As China comes under mounting pressure from the U.S. it may snap but claim that it is merely copying spying techniques developed by the U.S.

China's alleged espionage would not be the first time the U.S. has been burned by its own technology.

In the closing days of World War II, classified information on nuclear weapons technology developed by the U.S. was stolen through Soviet espionage operations under dictator Josef Stalin, making President Harry Truman's dream of a U.S. nuclear monopoly short-lived.

The U.S. has been slow to learn lessons from history. More than once, new American military technologies developed at a huge cost have been immediately stolen by China through espionage operations. This is massively damaging to the U.S. and its allies.

Washington is making serious efforts to end this cycle; it has been pressuring allies to exclude Chinese suppliers as they build out next-generation 5G telecommunications networks.

Western contractors have been taken aback on a massive scale. But inaction could pave the way for the Chinese, fully armed with U.S. technology, to destroy crucial infrastructure and undermine military capability, experts say.

China's foreign ministry on Dec. 21 denied the American allegations that Beijing has long carried out cyberattacks. Instead, Beijing accused Washington of espionage.

"For a long time, the U.S. has systematically monitored and stolen confidential information from foreign governments, companies and individuals on a large scale through the internet," the foreign ministry said in a statement. "That is an open secret."