"Micron has invested billions of dollars over decades to develop its intellectual property", Joel Poppen, Micron's general counsel, said in an emailed statement.
"Chinese espionage against the US has been increasing and has been increasing rapidly", Sessions said.
The prosecution comes amid heightened trade tensions and as American officials raise alarms about Chinese economic espionage. In the meantime, Washington is signaling that the gloves are off.
The new China initiative will be led by John Demers, assistant attorney general for national security, and carried out by a senior Federal Bureau of Investigation official, five USA attorneys and several top department officials.
The charges accuse the three named individuals of a conspiracy to steal Micron trade secrets relating to the development and manufacture of memory products.
The Chinese company Fujian Jinhua, and its Taiwanese partner, United Microelectronics Corporation (UMC) have been identified by the DOJ and charged with conspiring to illegally transfer designs and program information for Micron DRAM chips, produced by the Idaho-based company.
The state-owned firm named in the indictment, Fujian Jianhua, is a Chinese semiconductor manufacturer that was already targeted by the USA earlier this week when authorities slapped a ban on U.S. exports to the company.
The United States also sued on Thursday to block the transfer of trade secrets and to prevent the companies from exporting to the US any products that they manufacture by exploiting stolen information.
That man, identified by prosecutors as Chen Zhengkun (known in English as Stephen Chen), recruited both of his co-defendants to join him at UMC.
Jinhua has been on the United States government's radar for months. Chen worked for Micron before joining UMC, and "arranged a cooperation agreement between UMC and Fujian Jinhua", according to the indictment.
The trade secrets are worth up to $8.75 billion, the department said. The FBI, for example, could work with the State Department to revoke a suspect's visa, or with US companies to root out insider threats, he added.More news: Whoops! Mike Pence's Hollywood Slam Backfires In 'The Hollywood Of The South'
The indictment alleges China was interested in gaining access to dynamic random-access memory, or DRAM, a type of technology it did not possess.
According to the indictment, the Taiwanese nationals downloaded more than 900 confidential files from Micron.
"This was", said U.S. Attorney for the Northern District of California Alex Tse, "some of the most advanced semiconductor technology in the world".
The accused individuals face up to 15 years in prison and $5 million in fines, while the companies could incur up to $20 billion in financial penalties, Sessions added. A Taiwanese company and three individuals were also allegedly involved in the scheme.
In retaliation, the US Commerce Department on Monday placed heavy restrictions on Fujian Jinhua's ability to buy US machinery and materials for its factories that would boost its DRAM production capabilities. Without equipment sold only in the United States, Jinhua can not build the DRAM chips.
The charges were the latest in a series of cases targeting what Washington calls an ongoing Beijing programme to steal valuable U.S. industrial and commercial secrets in order to advance the Chinese economy.
"It's inadmissible", Sessions said.
The foreign agents' effort will be to "counter covert efforts to influence our leaders and the general public", Sessions said. Last month, the Treasury Department released interim rules to implement the new law. A Justice Department spokesman said the defendants were served summonses in Taiwan and that none is in USA custody.
The Justice Department also will target Chinese threats to US companies that provide components for sensitive technologies, especially those in the telecommunications sector as it readies for the transition to 5G networks. It's supply chain risk.
The criminal case is US v. The U.S. has taken an increasingly confrontational stance toward what it characterizes as China's "predatory" economic policies.
"Obviously, that commitment has not been met", he said.
"China is back as the most prolific nation-state actor conducting industrial espionage via cyber and non-cyber means", he said.